/)  10.  3  '//I 


/ 


U.  S.  DEPARTMENT   OF    AGR 

OFFICE  OF  EXPERIMENT  STATIONS    BULLE 

A.  C.  TRUE,   Director 


EXPERIMENTS  ON  THE  EFFECT  OF  MUSCULAR  WORK 

UPON  THE  DIGESTIBILITY  OF  FOOD  AND 

THE  METABOLISM  OF  NITROGEN. 


CONDUCTED  AT  THE 

UNIVERSITY    OF    TENNESSEE, 

1899-K )( )<  >. 


By  CI  IAS.  E.  WAIT,  Ph.  TX,  F.  C.  S., 

Professor  of  Chemistry  at  the  University  of  T.  tmeh^e. 


WASHINGTON: 

GOVERN  M  E  N  T     PRINTING     OFFIC  E 

1  9  0  2 . 


OFFICE  OF  EXPERIMENT  STATIONS. 

A.  C.  True,  Ph.  D.,  Director. 

E.  W.  Allen,  Ph.  D.,  Assistant  Director  and  Editor  of  Experiment  Station  Record. 
C.  F.  Lang  worthy,  Ph.  D.,  Editor  and  Expert  on  Foods  and  Animal  Production. 

NUTRITION    INVESTIGATIONS,   MIDDLETOWN,   CONN. 

W.  O.  Atwater,  Ph.  D.,  Chief  of  Nutrition  Investigations. 
C.  D.  Woods,  B.  S.,  Special  Agent  at  Orono,  Me. 

F.  G.  Benedict,  Ph.  D.,  Physiological  Chemist. 
R.  D.  Milner,  Ph.  B.,  Editorial  Assistant. 

2 


i 


R  OF  TRANSMITTAL 


U.  s.  Department  of  Agrioultube, 

Office  of  Experiment  Stations, 

Washington,  D.  0.,  July  5,  1902. 

Sir:  I  have  the  honor  to  transmit  herewith  a  report  on  experiments 
on  the  effect  of  muscular  work  upon  the  digestibility  of  food  and  the 
metabolism  of  nitrogen  eondueted  at  the  University  of  Tennessee  in 
1899  and  1900  by  Charles  E.  Wait,  professor  of  chemistry,  under  the 
immediate  supervision  of  Prof.  W.  O.  Atwater,  chief  of  nutrition  inves- 
tigations. These  studies  form  a  part  of  the  nutrition  investigations, 
conducted  under  the  auspices  of  this  Office,  to  gather  information 
regarding  the  food  habits  in  different  regions,  the  comparative  values 
of  different  foods,  the  laws  of  nutrition,  and  related  topics.  In  making 
these  investigations  Professor  Wait  was  assisted  by  Messrs.  C.  O.  Hill, 
W '.  K.  Hunter,  C.  A.  Mooers,  and  C.  G.  Schenk,  of  the  department  of 
chemistry  of  the  University  of  Tennessee.  The  present  investigations 
supplement  earlier  work  at  the  same  institution  on  the  effect  of  muscu- 
lar work  on  digestion  and  metabolism,  questions  which  are  of  great 
importance,  and  concerning  which  there  is  little  information  available. 
It  is  believed  that  the  present  investigation  is  a  valuable  contribution 
to  the  subject. 

The  report  is  therefore  submitted  with  the  recommendation  that  it 
be  published  as  Bulletin  No.  117  of  this  Office. 

Respectfully.  A.  C.  True, 

Director. 
Hon.  James  Wilson, 

Secretary  of  AgricuLtun . 


CONTENTS. 

Page. 

Introduction 7 

Preparation,  sampling,  and  analysis  of  food  materials.. 8 

Composition  of  food  materials  and  feces 9 

Details  of  the  experiments  carried  on  in  1899-1900 11 

Experiment  No.  17 11 

Experiment  No.  18 14 

Experiment  No.  19 17 

Experiment  No.  20 20 

Experiment  No.  21 23 

Experiment  No.  22 ! 26 

Experiment  No.  23 29 

Experiment  No.  24 32 

Experiment  No.  25 35 

Summary  of  coefficients  of  digestibility 38 

Metal  >olism  of  nitrogen  . . .  .• 39 

( '< miposite  samples 40 

5 


fSCULAR  WORK  AND  ITS  EFFECT  UPON  DIGES- 
TION AND  METABOLISM 


INTRODUCTION. 

With  a  view  to  learning  something  of  the  food  requirements  when 
muscular  work  Is  performed  and  of  the  digestibility  of  the  diet  and 
the  income  and  outgo  of  nitrogen  under  conditions  of  varying  muscu- 
lar work,-  experiments  have  been  carried  on  for  several  years  at  the 
University  of  Tennessee.  The  effect  of  muscular  work  upon  the 
metabolism  of  nitrogen  has  been  often  studied  in  the  past,  as  has  also 
the  question  of  diet  when  different  amounts  of  muscular  work  are 
performed.  Many  of  the  previous  nutrition  investigations  conducted 
under  the  auspices  of  this  Department  have  had  to  do  with  these 
problems/'  It  appears  that  comparatively  few  experiments  with  man 
have  been  made  to  determine  the  influence  of  muscular  work  upon  the 
digestion  of  food. 

The  results  of  the  earlier  experiments  on  this  subject  at  the  Univer- 
sity of  Tennessee  have  been  reported  in  previous  publications  of  this 
Office.6  The  present  bulletin  reports  the  results  of  nine  additional 
experiments  (Nos.  17-25,  inclusive)  conducted  in  1900,  which  wrere 
divided  into  three  sets  of  three  experiments  each.  With  one  excep- 
tion, each  of  the  experiments  covered  twelve  consecutive  days,  being 
divided  into  three  periods  of  four  days  each.  In  every  case  muscular 
work  was  performed  during  the  second  period,  while  in  the  first  and 
third  periods  as  little  muscular  work  was  performed  as  possible. 

In  the  first  series  of  experiments  (Nos.  17-19)  the  diet  furnished  a 
normal  amount  of  protein  and  energy,  and  was  the  same  in  all  three 
periods.  In  the  second  series  (experiments  Nos.  20-22)  the  diet  in  the 
first  and  third,  or  rest  periods,  furnished  several  grams  less  nitrogen 
and  500-600  calories  less  energy  than  a  normal  diet.  During  the  sec- 
ond or  work  period  the  nitrogen  content  of  the  ration  was  unchanged, 
while  the  energy  value  was  increased  some  500  or  600  calories.  In  other 
words,  the  energy  was  brought  up  to  the  normal.  In  the  third  series 
of  experiments  (Nos.  23-25)  the  diet  was  uniform  throughout  the 
experiment,  and  in  both  rest  and  work  periods  furnished  less  protein 
and  less  energy  than  a  normal  diet. 

"  U.  8.  Dept.  Agr.,  Office  of  Experiment  Stations  Buls.  75,  89,  98,  and  109. 
ft  U.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Buls.  53  and  89. 

7 


8 

The  subjects  of  the  experiments  were  the  same  three  healthy  young 
men  with  whom  the  earlier  tests  had  been  made. 

The  food  consisted  of  such  articles  as  gelatin,  milk,  oatmeal,  potato 
chips,  rice,  coffee,  butter,  eggs,  and  sugar,  combined  in  such  a  way  as 
to  form  a  simple  mixed  diet  of  reasonable  palatability.  The  diet  was 
somewhat  simpler  than  in  the  experiments  previouly  reported.0 

The  digestibility  of  the  ration  was  determined  by  the  usual  meth- 
ods, which  have  been  described  in  earlier  publications  of  this  Office. '' 
The  food  and  feces  were  analyzed,  the  latter  being  separated  by  means 
of  charcoal  taken  in  gelatin  capsules. 

The  income  and  outgo  of  nitrogen  was  also  studied.  In  addition  to 
determining  the  total  amount  of  urine  and  its  nitrogen  content,  deter- 
minations were  made  of  the  amount  and  proportions  of  nitrogen  in  the 
urine  corresponding  tc  eight-hour  periods  during  the  second  or  work 
periods,  as  it  was  believed  that  any  effects  of  muscular  work  on  the 
excretion  of  nitrogen  might  be  thus  more  readily  observed.  Similar 
determinations  were  made  during  the  third  period  to  learn  whether 
the  muscular  work  produced  effects  which  were  noticeable  after  the 
work  had  ceased.  In  most  of  the  experiments  these  determinations 
were  also  made  for  purposes  of  comparison  in  the  first  rest  period. 

The  external  muscular  work  consisted  in  walking  up  and  down  a 
hill  140  feet  high  on  a  smooth  path.  The  amount  of  muscular  work 
which  can  be  measured  in  such  cases  is  the  product  of  the  body  weight 
of  the  subject,  the  number  of  feet  which  his  body  is  vertically  raised 
each  trip,  and  the  number  of  trips,  that  is.  weight  multiplied  by  num- 
ber of  trips  uphill  multiplied  by  140  feet  equals  foot-pounds  of  work. 
So  far  as  is  known,  the  energy  expended  for  the  motion  of  forward 
progression  has  never  been  satisfactorily  measured  with  man.  The 
amount  of  work  performed  by  a  man  walking  downhill  is  also  unknown. 
It  is  certain,  therefore,  that  more  work  was  performed  by  the  subject 
than  is  shown  by  the  method  of  calculation  followed.  While  it  is  to 
be  regretted  that  the  total  amount  of  work  could  not  be  accurately 
measured,  the  results  are  sufficient  for  the  purposes  of  the  experiments, 
since  the  object  was  to  require  of  the  subject  an  amount  of  muscular 
work  sufficient  to  produce  fatigue  and  to  compare  the  results  with 
different  subjects  under  the  experimental  conditions.  So  far  as  an 
extended  review  of  the  literature  shows,  the  factors  which  were  not 
measured  in  these  experiments  have  not  been  taken  into  account  in  simi- 
lar experiments  reported  by  other  investigators. 

PREPARATION.  SAMPLING.  AND  ANALYSIS  OF  FOOD  MATERIALS. 

As  stated  above,  the  diet  followed  in  these  experiments  was  simple 
and  made  up  of  a  comparatively  small  number  of  articles.     The  foods 

r.  S.  Dent  A-r..  oilier  of  Experiment  Stations  Buls.  53  and  89. 
h  V.  s.  Pept.  A.srr..  Office  of  Experiment  Stations  Buls.  21  and  B5. 


9 

chosen  were  of  such  ;i    nature  that  it   is  believed    little  difficulty  would 

be  experienced  in  obtaining  a  comparatively  Large  supply  of  practi- 
cally uniform  composition,  a  matter  of  considerable  importance  in 
experiments  in  which  it  is  desired  to  have  a  diet  furnishing  uniform 

amounts  of  nutrients  and  energy.  The  milk,  butter,  coffee,  sugar, 
rice,  and  eggs  were  the  usual  products.  The  bread  was  made  from 
patent  wheat  flour  and  was  the  so-called  Vienna  loaf.  The  gelatin  was 
one  of  the  ordinary  commercial  products,  as  was  also  the  rolled  oats 
used.  The  potato  chips  were  prepared  by  frying  very  thin  slices  of 
potato  in  deep  fat  until  light  brown,  (are  was  taken  to  secure  repre- 
sentative samples  of  all  food  materials  for  analysis.  The  milk  was 
purchased  fresh  each  day,  an  aliquot  portion  taken  as  a  sample,  and 
these  portions  united  to  form  a  eomposite  sample  for  the  whole  period. 
The  oatmeal  was  sampled  before  cooking.  In  the  case  of  bread,  rep- 
resentative slices  from  each  loaf  served  as  samples. 

COMPOSITION  OF  FOOD  MATERIALS  AND  FECES. 

The  composition  of  the  foods  and  feces  was  determined  by  the 
analytical  methods  adopted  by  the  Association  of  Official  Agricultural 
Chemists."  with  such  modifications  as  have  been  suggested  by  Atwater 
and  Woods/'  and  with  minor  variations  which  experience  in  this  labora- 
tory has  shown  to  be  desirable. 

The  heats  of  combustion  of  the  samples  of  food  materials  and  excre- 
tory products  were  not  determined  in  these  experiments.  The  values 
for  energy  given  in  the  tables  of  the  different  experiments  were  cal- 
culated. The  energy  of  the  food  materials  was  calculated  from  the 
total  nutrients  of  the  diet  by  the  factors  5.65  calories  per  gram  of 
protein.  9.40  calories  per  gram  of  fat,  and  4.15  calories  per  gram  of 
carbohydrates.'  The  energy  of  the  feces  for  the  rest  and  work  experi- 
ments was  calculated  from  the  total  organic  matters  of  the  feces  byT 
use  of  the  average  heat  of  combustion  per  gram  of  feces  in  the  rest 
and  work  experiments  of  1897-1899,  viz/7  5.19  calories  per  gram  in 
the  rest  experiments  and  bA'2  calories  per  gram  in  the  work  experiments. 
The  energy  of  the  urine  was  computed  by  assuming  that  for  every 
gram  of  protein  in  the  digested  material  there  would  be  1.25  calories 
of  energy  lost  in  the  organic  matter  of  the  urine/ 

'Fable  1  shows  the  composition  of  the  food  materials  and  Table  2  the 
composition  of  the  water-free  feces.  The  proportion  of  nitrogen  in 
the  food  materials  and  feces  is  included  in  the  tables,  as  well  as  the 

"U.  S.  Dept.  Agr.,  Division  of  Chemistry  Bui.  46,  revised. 

^Connecticut  (Storrs)  Station  Report,  1891,  p.  47,  and  U.  8.  Dept.  Agr.,  Office  of 
Experiment  Stations  Bui.  21. 

'Connecticut  (Storrs)  Station  Report,  1899,  p.  104. 

,f  V.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  89,  p.  15. 

eV.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  53,  p.  28. 


10 

protein  which  represents  the  total  nitrogen  multiplied  by  the  factor 
6.25.  It  is  recognized  that  the  use  of  this  factor  involves  more  or  less 
error,  especially  in  the  ease  of  cereals;  but  as  it  has  been  more  gener- 
ally used  than  any  other  factor  in  computing  the  results  of  digestion 
experiments  it  has  been  retained.  Should  it  seem  desirable  at  any 
time  to  recalculate  the  results,  making  use  of  other  factors,  this  can 
be  readily  done  from  the  statistics  published  in  this  report. 

Table  1. — Composition  of  food  material*. 


Labora- 
tory 
num- 
ber. 

Food  materials. 

Water. 

Nitrogen. 

Protein 

(NX6.25). 

Fat. 

Carbohy- 
drates. 

Ash. 

449 

Per  cent. 

73.67 

11.69 

8.27 

11.05 

85.88 

86.26 

86.30 

86.18 

86.23 

85.96 

86.51 

86. 42 

85.98 

1.00 

6.94 

8.25 

8.62 

32.49 

31.81 

31.81 

4.88 

3.73 

3.01 

Per  cent. 

2.08 

.22 

.24 

.30 

.59 

.55 

.57 

.58 

.56 

.56 

.55 

.54 

.54 

.75 

2.27 

2.45 

1.33 

1.52 

1.51 

1.59 

.78 

1.20 

1.25 

Per  cent. 
13.00 
1.39 
1.56 
1.89 
3.69 
3.44 
3.56 
3.63 
3.50 
3.50 
3.44 
3.38 
3.38 
4.69 
14.19 
15.31 
8.31 
9.51 
9.42 
9.94 
4.88 
7.50 
7.81 

Per  cent. 

11.17 

83.86 

87.43 

84.79 

4.61 

4.54 

4.46 

4.72 

4.94 

4.94 

4.65 

4.65 

5.02 

.36 

7.01 

7.18 

.41 

1.17 

1.25 

1.27 

30.78 

36.68 

33.34 

l'i  r  end. 

Per  cent. 
0.99 

486 

Butter 

3.06 

508 

.do...               

2.74 

528 

do .                             

2.27 

481 

Milk 

5.10 
5.02 
4.86 
4.67 
4.85 
4.85 
4.63 
4.82 
4.83 
93.82 
69.99 
67.39 
82. 16 
55.  96 
56.55 
55.92 
56.37 
47.80 
51.05 
100.00 

.72 

494 

do 

.74 

499 

...do... 

.82 

504 

do 

.80 

515 

do  . . .                            

.75 

520 

...do 

.75 

525 

do 

.77 

535 

..do...                           

.73 

540 

do 

.79 

480 

.13 

482 

1.87 

505 

...do..            

1.87 

485 

Rice 

.50 

484 

.87 

507 

do 

.97 

527 

...do 

1.06 

483 

3.09 

506 

do 

4.29 

526 

...do 

4.79 

Coffee  .. 

Table  2. — Composition  of  water-free  substance  of  feces. 


Labora- 
tory 
num- 
ber. 


490 
491 
492 
495 
496 
497 
500 
501 
502 
511 
512 
513 
516 
517 
518 
521 
522 
523 
531 
532 
533 
536 
537 
538 
541 
542 
543 


Sample. 


Feces  . 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 


Nitrogen. 

Protein 

(NX6.25). 

Fat. 

Carbohy- 
drates*. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

4.77 

29.83 

15. 72 

29.05 

4.98 

31.13 

25.53 

23.78 

4.69 

29.32 

24.24 

26.73 

4.98 

31.13 

14.60 

29.11 

4.96 

31.02 

25.69 

23.41 

4.44 

27.77 

30.50 

21.65 

4.92 

30.78 

13.51 

29.16 

5.10 

31.89 

23.  98 

23. 03 

4.83 

30.22 

23.97 

25.  40 

4.76 

29.  76 

22.91 

19.29 

5.00 

31.24 

30.38 

15.30 

4.71 

29.40 

31.99 

16.93 

4.88 

30.  48 

22.53 

21.98 

4.87 

30.44 

33.23 

14.18 

4.59 

28.67 

36.13 

15.67 

5.00 

31.27 

19.66 

22.43 

4.93 

30.80 

29.  23 

16.58 

4.82 

30.14 

25.  49 

22.03 

4.91 

30.  71 

18.38 

23.81 

5.09 

31.80 

18.64 

26.76 

4.85 

30.33 

16.57 

28.91 

4.93 

30.84 

20.07 

22.66 

5.12 

32.01 

27.  55 

18.99 

5.  02 

31.35 

28. 13 

18.03 

4.86 

30.39 

21.77 

20.59 

5.20 

32.49 

27.13 

19.43 

4.87 

30.41 

34.03 

14.55 

Per  cent. 
25.40 
19.56 
19.71 
25.16 
19.88 
20.08 
26.55 
21.10 
20.41 
28.04 
23. 08 
21.68 
25.01 
22.15 
19.53 
26.64 
23.39 
22.34 
27.10 
22.  80 
24.19 
26.43 
21.45 
22.  49 
27.25 
20.95 
21.01 


11 

DETAILS  OF  THE    EXPERIMENTS  CARRIED  ON  IN   1899  1900. 

The  experiments  recorded  in  the  present  report  were  conducted  in  the 
winter  of  L899  L900,  and  were  so  arranged  that  each  experiment  wa> 
carried  on  with  the  three  different  subjects  simultaneously.  'The  sup- 
per preceding  each  experiment  consisted  largely  of  bread  and  milk, 
and  the  experimental  period  in  every  case  commenced  with  breakfast. 
With  this  meal  the  lampblack  used  to  color  the  feces  and  to  permit  a 
separation  of  portions  pertaining  to  the  diet  under  investigation  was 
taken.  In  the  earlier  investigations  the  experiment  proper  was  pic- 
ceded  by  a  period  in  which  the  diet  was  adjusted  SO  that  the  subject 
was  in  nitrogen  equilibrium.  This  plan  was  not  followed  in  the  pres- 
ent investigation,  as  (judging  by  the  experience  then  gained)  it  was  not 
necessaiy. 

EXPERIMENT  NO.    17. 

This  experiment  was  carried  on  with  a  chemist  30  years  of  age,  in 
good  health.  The  experiment  was  divided  into  three  periods  of  four 
days  each.  During  the  second  period  the  subject  made  74  trips  up 
and  down  hill.  This  was  calculated  as  equivalent  to  1,617,122  foot- 
pounds or  55,S76kilogrammeters  of  work.  The  mechanical  equivalent 
of  one  calorie  is,  in  round  numbers,  8.100  foot-pounds.  The  heat 
equivalent  for  the  work  measured  for  the  four  days  was,  therefore, 
130  calories,  or  82  calories  per  day.  As  previously  stated,  the  actual 
work  performed  must  have  been  considerably  more  than  the  amount 
thus  estimated. 

Subject. — Chemist,  30  years  of  age. 

Weight  i  without  clothing  ). — At  the  beginning  of  the  experiment  68.6  kilograms  (151 
pounds);  at  the  end  of  the  first  period  68.2  kilograms  (150  pounds).  During  the 
remainder  of  the  experiment  the  weight  remained  unchanged. 

Duration. — Tin-  experiment  began  with  breakfast,  December  9;  the  second  period 
with  breakfast.  December  13,  and  the  third  period  with  breakfast.  December  17. 
Each  period,  therefore,  occupied  four  days. 


12 


Table  3. — Results  of  experiment  No.  17. 


Labor- 
atory 
num- 
ber. 

Pood  materials. 

Weighl 

of  ma- 
terial. 

Total 
organic 

matter. 

Nitro- 
gen. 

Protein. 

Fat 

Carbohy- 
drates. 

Ash. 

Heat  of 

com- 
bustion 
calcu- 
lated. 

149 

First  Period 

(Rest). 

Digt  Mi  an  <  xperiment 

NO.  206. 

drum*. 
364 
120 

8,000 
100 
320 
120 

1,200 

40 

320 

800 

drum*. 

88 

103 

1,072 

99 

291 

109 

800 

37 

320 

2 

Grams. 

l.lu 

.26 

47.  20 

.7:. 

7.26 

1.60 

18.  2 4 

.31 

lira  ins. 

47 

2 

295 

5 

i:» 

10 

111 

2 

drums. 
41 
101 
369 

Grams. 

drums. 

1 

1 

58 

Calories. 

186 

Butter     . 

481 

Milk 

408 
94 

221 
99 

672 
23 

320 

480 

Gelatin 

482 

22 

6 
1 

10 

1 

485 

Rice 

484 

Bread 

11 
12 

483 

Potato  chips 

Coffee 

.32 

2 

Total  . . 

2,921 

83.51 

522 

559 

1,840 

84 

15,839 

Feces  (water-free). 

490 

147 
7,020 

110 

7.01 
70. 25 

44 

23 

43 

37 

571 
597 

Amount  digested . 

Coefficients  of  di- 
gestibility   (per 

2,811^ 
96.2 

76.50 
91.6 

478 
91.6 

536 
95.9 

1,797 
97.7 

47 
56.0 

14,671 

92.  6 

Second  Period 
(Work). 

Digestion  experinu  nt 
No.  207. 

449 

364 
120 

8,000 
100 
320 
120 

1,200 

40 

320 

800 

88 

103 

1.040 

99 
291 
109 
800 

37 

320 

2 

7.57 

.26 

44.00 

.75 

7.26 

1.60 

IS.  24 

.31 

47 

2 

275 

5 

45 

10 

114 

2 

41 
101 
363 

A 

4 

59 

486 

Butter. 

494 

Milk 

402 
94 

224 
99 

672 
23 

320 

480 

Gelatin  ... 

482 

Oatmeal 

Rice 

Bread 

Potato  chips 

Sugar 

Coffee 

Total 

22 

6 

1 

10 

1 

485 

484 

14 
12 

483 

.32 

2 

2,889 

80.31 

502 

553 

1.834 

85 

15. 646 

Feces  (water-free). 
Urine 

Amount  digested . 

Coefficients  of  di- 
gestibility   (per 
cent) 

495 

140 
5,837 

105 

6.97 
71.68 

-14 

20 

41 

35 

569 

572 

2,784 

73.34 

458 

533 

1,793 

50 

14,505 

96.4 

91.3 

91.2 

96.4 

97.8 

58.8 

92.7 

Third  Period 

(Rest). 

Digestion  experiment 
No.  208. 

449 

364 

120 

8,000 

100 

320 

120 

1.200 

40 

320 

800 

88 

103 

1,031 

99 
291 
109 
800 

37 

320 

2 

7.57 

.26 

45.  60 

.  75 

7.26 

1.60 

18.24 

.31 

47 

2 

285 

5 

45 

10 

114 

2 

41 
101 

357 

4 

4 

66 

486 

Butter... 

499 

Milk 

Gelatin 

389 
94 

224 
99 

672 
23 

320 

480 

482 

Oatmeal 

Rice 

Bread 

22 

6 

1 

485 

484 

14 
12 

4S3 

Potato  chips 

Sugar 

Coffee 

.32 

2 

Total 

2, 880 

81.91 

512 

547 

1.821 

92 

15, 592 

Feces  (water-free). 
Urine 

500 

130 

7.  233 

96 

6.40 

70.  4  a 

40 

18 

38 

34 

498 
590 

Amount  digested. 

Coefficients  of  di- 
gestibility   (per 
cent)  ..." 

2,  784 

75. 51 

472 

529 

1,783 

58 

14,504 



96.7 

92.  2 

92.  2 

96.7 

97.9 

63.0 

93.0 

13 

Throughout  this  experiment  the  urine  was  collected  in  portions  cor- 
responding to  eight-hour  intervals.  The  results  for  the  first  period 
(rest)  follow: 

Table  4. — Amount  of  nitrogen  eliminated  in  theurme  {digestion  experiment  No.  .'06). 


Period. 


First  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


8  a.  in. 

1  p.  in. 

12  p.  in. 

to 

to 

to 

1  I>.  III. 

12  p.  in. 

9  a.  in. 

550 

710 

602 

6.05 

6.82 

5.42 

1.10 
1,112 

.96 
688 

.90 
417 

6.34 

6.26 

4.63 

.57 

.91 

1.11 

508 

683 

357 

5.54 

6.76 

4.68 

1.09 

.99 

1.31 

385 

633 

375 

5.54 

7.22 

4.99 

1.44 

1.14 

1.33 

Total. 


1 ,  862 
18.29 


2, 217 
17.23 


1,548 
16.98 


1,393 
17.75 


The  quantity  of  urine  eliminated  and  its  nitrogen  content  during 
the  second  or  work  period  are  shown  in  the  following  table: 

Table  5. — Amount  of  nitrogen  eliminated  in  the  urine  {digestion  experiment  No.  201) . 


Period. 


First  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


8  a.m. 

4  p.m. 

to 

to 

4  p.m. 

12  p.  m. 

358 

567 

5.76 

6.46 

1.61 

1.14 

430 

593 

5.98 

7.18 

1.39 

1.21 

503 

625 

6.29 

7.00 

1.25 

1.12 

850 

469 

6.72 

6.52 

.79 

1.39 

12  p.m. 

to 
8  a.m. 


365 
5.04 
1.38 

313 
4.41 

1.41 

395 
5.41 
1.37 

369 
4.91 
1.33 


Total. 


1,290 
17. 26 


1,336 
17.  o7 


1,523 

18.70 


1,688 

18. 15 


14 


During  the  third  period,  which  was,  like  the  first,  a  period  of  rest,  the 
amount  of  urine  eliminated  and  its  nitrogen  content  were  as  follows: 

Table  <>.    -Amount  of  nitrogen  eliminated  in  the  urine  {digestion  experiment  No.  208). 


'eriod. 


8  a.  in. 
to 

i  |».  in. 


i  p. in. 

to 
12  j).  m. 


.grams 
..do.. 


.grams. 
.  .do. .. 


First  day: 

Weight  of  urine 

Weight  of  nitrogen 

Per  cent  of  nitrogen 

second  day: 

Weight  of  urine 

Weight  of  nitrogen 

Per  rent  of  nitrogen 

Third  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


667 
6.  II 
1.13 

635 

."».  52 
.87 

568 
5.  68 
1.00 

653 

5.  SI 


942 
6.  78 

.72 

5 13 

(i.  46 
1.19 

<it;;j 
6.90 
1.04 

688 
6.60 


12  p.  m. 

to 
8  a.m. 


(63 

1.  63 
1.00 

495 
5.10 
1.03 

542 

5.42 
1.00 

IT  I 
5.12 
1.08 


Total. 


1 .  972 
17.82 


1,673 


1.77:5 
18.00 


1,815 

17.:.:-! 


The  above  data  regarding  the  income  of  nitrogen  in  the  food  and  the 
excretion  of  nitrogen  in  the  urine  and  feces  served  for  computing  the 
average  balance  of  the  income  and  outgo  of  this  element.  The  effect 
of  muscular  work  on  the  excretion  of  nitrogen  is  discussed  when  the 
experiments  are  considered  as  a  whole.     The  nitrogen  balance  follows: 

Table  7. — Daily  income  and  outgo  of  nitrogen  in  experiment  No.  17. 


Periods. 


Time.. 

Nitrogen. 

In  food. 

In  feces. 

In  urine. 

Gain. 

Days. 
4 
4 
4 

Grams. 

20.88 
20.08 
20.48 

<t  rum*. 
1.75 
1.74 
1.60 

Grams. 

17.56 
17.  92 
17.61 

Grams. 
1.57 
.42 
1.27 

First  period,  rest  . . . 
Second  period,  work 
Third  period,  rest  . .. 


EXPERIMENT  NO.  18. 

This  experiment  was  carried  on  at  the  same  time  as  experiment  No. 
17.  The  subject,  a  chemist,  23  years  of  age,  was  in  normal  health. 
During  the  first  and  third  periods  of  the  experiment  little  or  no  external 
muscular  work  was  performed.  During  the  second  period  the  subject 
made  SO  trips  up  and  down  hill.  This  was  calculated  to  furnish 
1,439,100  foot-pounds  or  48,849  kilogramme ters  of  work,  equivalent  to 
114  calories,  or  an  average  of  28  calories  per  da}T. 

Subject. — Chemist  B,  23  years  of  age. 

Weight  (without  clothing). — At  the  beginning  of  the  experiment,  55.2  kilograms 
(121 2  pounds);  at  the  end  of  the  first  period  and  the  beginning  of  the  second  period, 
56.1  kilograms  (123^  pounds);  at  the  end  of  the  second  and  the  beginning  of  the 
third  period,  56.4  kilograms  (124  pounds);  at  the  close  of  the  experiment,  56.6  kilo- 
grams (124$  pounds). 

Duration. — The  experiment  began  with  breakfast  December  9,  and  the  first  period 
continued  four  days.  The  second  period  began  with  breakfast  December  3  and  con- 
tinued four  days.  The  third  period  began  with  breakfast  December  17  and  continued 
tout  days. 


15 


-Results  of  experiment  No.  18. 


Labora- 
tory 

num- 
ber. 

Pood  materials. 

Weight 
of  ma- 
terial. 

Total 
organic 
matter. 

Nitro- 
gen. 

Protein. 

Pat 

Carbohy- 
drates. 

Ash. 

Heal  ol 

COmbllS- 

tion 
calcu- 
lated. 

1 19 

First  Period 
(Rest). 

Digestion  experi- 
ment No.  209. 

<i  nun*. 
606 
120 

6,000 
100 
320 
120 

1,000 
120 
400 
400 

Grams. 

1  17 
103 
804 
99 
291 
109 
667 
111 
400 
1 

drums. 

12. 60 

.26 

35. 40 

.75 

7.26 

1.60 

15.20 

.94 

Grams. 

79 

2 

221 

5 

45 

10 

96 

6 

Qrams. 
68 

101 

277 

inn  ins. 

Gravis. 
6 
4 

43 

Calories. 

186 

Butter 

481 

Milk 

306 
94 

224 
99 

560 
68 

400 

ISO 

Gelatin 

482 

1  >;itmeal 

22 

6 

1 
9 
4 

485 

Rice 

bread 

Potato  chips 

484 

12 

:\7 

483 

Coffee 

.16 

1 

Total 

2,  732 

74. 17 

164 

517 

1,751 

73 

14, 749 

Feces  (water-free) 
Urine 

491 

121 

4,981 

97 

6.03 
52.02 

37 

31 

29 

24 

503 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 

2, 635 

68.14 

427 

486 

1,722 

49 

13,  712 

96.5 

91.9 

92.0 

94.0 

98.3 

(17.1 

93.0 

Second  Period 
(Work). 

Digestion  experi- 
ment No.  210. 

449 

606 
120 

6,000 
100 
320 
120 

1,000 
120 
400 
400 

147 
103 
780 
99 
291 
109 
667 
111 
400 
1 

12.60 

.26 

33.00 

.75 

7.26 

1.  60 

15.20 

.94 

79 

2 

206 

5 

45 

10 

95 

6 

68 
101 
273 

6 

4 

44 

486 

Butter 

494 

Milk 

301 
94 

224 
99 

560 
68 

400 

480 

Gelatin 

482 

22 

6 
1 
9 
4 

485 

Rice... 

484 

Bread 

12 
37 

483 

Potato  chips 

Coffee 

.16 

1 

Total 

2,708 

71.77 

449 

513 

1,746 

74 

14,  605 

Feces  (water-free) 

496 

122 
4,383 

98 

6.05 
57.12 

38 

31 

29 

24 

531 
514 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent) 

2,610 

65.  72 

411 

482 

1,717 

50 

13,560 

96.4 

91.6 

91.5 

94.0 

98.3 

67.  6 

92. 9 

Third  Period 
|(Rest). 

Digestion  experi- 
ment No.  211. 

449 

606 
120 

6,000 
100 
320 
120 

1,000 
120 
400 
400 

147 
103 
773 
99 
291 
109 
667 
111 
400 
1 

12.60 

.26 

34.20 

.75 

7.26 

1.60 

15.20 

.94 

79 

2 

214 

5 

45 

10 

95 

6 

68 
101 
268 

6 

4 

49 

486 

Butter 

499 

Milk 

291 
94 

224 
99 

560 
68 

400 

480 

Gelatin 

482 

Oatmeal  

22 

6 

I 

4 

485 

Rice 

484 

Bread  . . 

12 

37 

483 

Potato  chips 

Sugar 

Coffee 

.16 

1 

Total 

2,  701 

72.  97 

457 

508 

1,736 

79 

14.561 

Feces  (water-free) 
Urine 

501 

123 
5,068 

97 

6.27 
56.  70 

39 

30 

28 

26 

503 
522 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent) 

2,  604 

66.70 

418 

478 

1,708 

53 

13, 536 

96  4 

91.4 

91.5 

94.1 

98.4 

67.1 

93.0 

16 

A>  in  the  preceding  experiment,  the  urine  was  collected  in  the  three 
periods  in  portions  corresponding  to  eight-hour  intervals.  The  data 
for  the  urine  in  the  first  period  follows: 

Table  i>. — Amount  of  nitrogen  eliminated  in  th  urim  (digestion  <  rperiment  No.  209). 


Period. 


First  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine gra ms.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


8  a.  in.       a  p.  in.      12  i>.  m. 

to  to  to 

\  ]>.  m.       12  p.  in.       8  ]».  in. 


Total. 


530 
4.24 


5.81 
.64 

478 

4.06 

.85 


325 
4.23 
1.30 

562 

4.66 

.83 

281 
3.96 
1.41 


574 

338 

>.61 

4.83 

.96 

1.43 

270  1.125 

3. 73  12.20 

Li 


220  1.690 
3.23  13.70 
1.47    


1,019 
11.95 


260 
3.93 
1.51 


1.147 
3.83  14.17 
1.63    


The  total  amount  of  urine  and  its  nitrogen  content  eliminated  during 
the  second  or  work  period  follows: 

Table  10. — Amount  of  nitrogen  eliminated  in  tin-  urine  (digestion  experiment  No.  810). 


Period. 


8  a.  m. 
4  p.  m. 


First  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen : 


510 
5.46 
1.07 

545 
5.67 
1.04 

532 
5.91 
1.11 

575 
6.15 
1.07 


4  p.  m.      12  p.  m. 

to  to  Total. 

12  p.  m.      S  a.  m. 


380 
5.66 
1.49 

259 
4.20 
1.62 

295 
4.48 
1.52 

436 
5.14 
1.18 


190  1,080 
3. 14  14.  26 
1.65    

241  ,  1.045 

3.88  I  13.75 

161 

225  1,062 

3.94             14.33 
1.75    

195  1,206 
3. 49  14.  78 
1.79    


17 

The  third  period  like  the  first  was  a  period  of  rest.  The  urine 
eliminated  in  periods  corresponding  to  eight-hour  interval-,  and  its 
nitrogen  content,  i*>  shown  in  the  following  table: 

Table  11. — Amount  of  nitrogen  eliminated  in  th  urine  (digestion  experiment  No.  911). 


Period. 


12  p.  m.  I 

to  Total. 

a.  m. 


First  day: 

Weight  in"  urine grams..  503 

Weighl  of  nitrogen  <1<>  — 

Per  cent  of  nitrogen 1.13 

Second  day: 

Weight  of  urine grams..  723 

Weight  of  nitrogen do  —  5.49 

Percent  of  nitrogen .76 

Third  day: 

Weight  of  urine grain-..  .">!•"> 

Weight  of  nitrogen do 5.  4-") 

Per  cent  of  nitrogen 1.00 

Fourth  day: 

Weight  of  urine grams..  632 

Weight  of  nitrogen do 5, 

Percent  of  nitrogen .90 


1,3-51 

11.71 


lo.VI 


1, 163 
13.98 


1,222 
14.12 


From  the  data  recorded  above  the  balance  of  income  and  outgo  of 
nitrogen  was  determined.     The  results  follow: 


Table  12. — Daily  income  and  outgo 

of  nitrogen  in  >\ 

pi  rilin  nt 

No.  18. 

Period. 

Nitrogen. 

In  food. 

In  feces. 

In  urine. 

Gain. 

First  period,  rest 

Second  period,  work 

Third  period,  rest 

Days.      Grams. 

4            18.54 
4           17.94 
4           18.24 

Gram*. 
1.51 

1 .  51 

1.57 

Grams. 

13.01 
14.28 
14.18 

Grams. 
4.02 
2.15 

2.  49 

EXPERIMENT  NO.  19. 

This  experiment  was  carried  on  with  a  student.  C,  age  22  years,  and 
in  good  health.  In  the  first  and  third  periods  as  little  muscular  work 
was  performed  as  possible.  During  the  second  period  the  subject 
made  80  trips  up  and  down  a  hill.  This  was  calculated  to  furnish 
1,471.080  foot-pounds,  or  50,992  kilogrammeters.  equivalent  to  a  total 
of  119  calories,  or  30  calories  per  day. 

Subject. — Student  ('.  22  years  of  age. 

Weight  {without  clothing). — At  the  beginning  of  the  experiment,  63.0  kilograms 
(138£  pounds);  at  the  close  of  the  first  period,  62.7  kilograms  (138  pounds).  During 
the  second  and  third  periods  the  weight  remained  unchanged. 

Duration. — The  experiment  began  with  breakfast  December  9;  the  first  period 
covered  four  days;  the  second  began  with  breakfast  December  13  and  covered 
four  days;  the  third  began  with  breakfast  December  17  and  covered  only  three  days. 
1326— No.  117—02 2 


18 


Table  Vd. —  Results  of  experiment  No.  19. 


Labora- 
tory 

num- 
ber. 

Food  materials. 

Weighl 

of  ma- 
terial. 

Total 

organic 
matter. 

Nitro- 
gen. 

Protein. 

Fat. 

Carbohy- 
drates. 

Ash. 

Heat  of 
combus- 
tion 
calcu- 
lated. 

449 

First  Period 

(REST;. 

Digestion  expert 

meat  No.  tit. 

Grams. 

519 
120 

6,000 
100 
320 
120 

1.200 
160 
400 
400 

Grams. 
125 
103 

804 
99 
291 
109 
800 
147 
400 
1 

Grams. 

10.80 

.26 

35. 40 

.75 

7.26 

1.60 

18.24 

1.25 

Grams. 

67 
2 
221 
5 
45 
10 
114 
8 

(i  nuns. 
58 
101 
277 

Qrams. 

Grams. 

5 

4 

43 

Calories. 

486 

Butter 

481 

Milk 

306 
94 

224 
99 

672 
90 

400 

480 

Gelatin 

182 

22 

6 

-        1 

10 

5 

485 

Rice 

484 

Bread 

14 
49 

483 

Potato  chips 

Coffee  . . 

.16 

1 

Total 

2,879 

75.72 

473 

521 

1.885 

74 

15. 392 

Feces(water-free) 

492 

123 
4,468 

99 

5.77 
57. 16 

36 

30 

33 

24 

514 
546 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent) 

Second  Period 

(WORKI. 

Digestion  experi- 

m  at  No.  US. 

Eggs 

Butter 

2,780 

69.  95 

437 

491 

1,852 

50 

14,332 

96.6 

92.  4 

92.  1 

94.3 

98.3 

67.6 

93.1 

449 

519 
120 

6,000 
100 
320 
120 

1.200 
160 
400 
400 

125 
103 
780 
99 
291 
109 

BOO 

147 
400 

1 

10.80 

.  26 

33.00 

.75 

7.26 

1.60 

18.  24 

1.25 

67 

2 

206 

5 

45 

10 

114 

8 

58 
101 
273 

5 

4 

44 

486 

494 

Milk 

301 
94 

224 
99 

672 
90 

400 

480 

Gelatin 

482 

22 

6 

1 

10 

5 

485 

Rice 

484 

Bread 

14 
49 

483 

Potato  chips 

Coffee  

.16 

1 

Total 

Feces (  water- free  i 
Urine 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent i 

2,  855 

73.  32 

458 

517 

1,880 

75 

15, 2.50 

497 

123 
4.040 

99 

5. 46 
65.  75 

34 

38 

27 

25 

537 
530 

2,  756 

67.86 

424 

479 

1,853 

50 

14.183 

96. 5 

92.6 

92.6 

92.7 

98.6 

66.7 

93.0 

Third  Period 

(Resti. 

Digestion  expt  rt 

iiii  nt  No.  21U. 

449 

389 

90 

4.500 

75 

240 

90 

900 

120 

300 

300 

94 
76 

580 

74 

219 

82 

600 

111 

300 

1 

8.09 

.20 

25.  65 

.  56 

5.  45 

1.20 

13.68 

.94 

51 

1 
160 

4 
34 

8 
86 

6 

43 

75 

201 

4 
37 

486 

Butter 

499 

Milk 

219 
70 

168 
74 

.504 
68 

300 

480 

Gelatin 

t82 

17 

4 

185 

Rice 

484 

Bread 

Potato  chips 

Sugar 

10 
37 

8 
4 

483 

Coffee 

.12 

1 

Total 

2.137 

55. 89 

351 

383 

1,403 

60 

11.405 

Feces  ( water-free ) 
Urine 

502 

84 
4.245 

07 

4.06 
.50.31 

25 

20 

n 

17 

348 
407 

Amount  digested. 

Coefficients  of  di- 
gestibility  (per 
cent | 

2. 070 

51.83 

326 

363 

1.381 

43 

10  650 

96.  9 

92.  7 

92.  9 

94.8 

98.4 

71.7 

93  4 

, 



19 

In  all  three  periods  of  this  experiment  the  urine  was  collected  in 
portions  corresponding  to  eight-hour  periods,  the  amount  and  its 
nitrogen  content  being  determined.  Results  from  the  first  (rest) 
period  follow: 

Table  14. — Amount  of  nitrogen  eliminated  in  the  urine  [digestion  experiment  No.  212). 


Period. 


First  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do — 

ivr  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  nrine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do — 

Per  cent  of  nitrogen 


8  a.  m. 

4  p.  m. 

12  p.  in. 

to 

to 

to 

1  p.  in. 

L2  i>.  in. 

8  a.  m. 

117 

330 

344 

5.  16 

6. 68 

4.20 

1 .  22 

1.72 

1.22 

:>t:> 

:.:,7 

246 

6.10 

4.01 

8. 57 

1.06 

.72 

1.45 

275 

333 

203 

4.10 

5.56 

3.19 

1.49 

1.67 

1.57 

368 

500 

300 

5.48 

6.40 

3.42 

1.53 

1.28 

1.14 

Total. 


1,121 
L5.38 


1,378 

13.68 


811 
12. 85 


1 ,  158 
15.  30 


The  amount  of  urine  eliminated  during-  the  second  (work)  period 
and  its  nitrogen  content  was  as  follows: 

Table  15. — Amount  of  nitrogen  eliminated  in  the  urine  (digestion  experiment  No.  213). 


Period. 


Total. 


First  day: 

Weight  of  urine gra  ms. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


20 


The  details  of  the  elimination  of  nitrogen  during  the  third  (rest) 
period,  which  covered  only  three  days,  are  given  in  the  following 
table: 

Table  lt>. — Amount  of  nitrogen  eliminated  in  the  urim  [digestion  experiment  No.  214) • 


Period. 


8  a.  m. 

to 
4  p.  m. 


First  day: 

Weighl  of  urine grams..  382 

Weight  of  nitrogen do 5.77 

Per  cent  of  nitrogen 1.51 

Second  day: 

Weight  of  urine grams. .  535 

Weight  of  nitrogen do 5.89 

Per  cent  of  nitrogen 1.10 

Third  day: 

Weight  of  urine grams. .  4.50 

Weight  of  nitrogen do 5.76 

Per  cent  of  nitrogen 1.28 


4  p.  m. 

to 
12  p.  m. 


12  p.  m. 

to 
8  a.  m. 


6.51 


443 
6.  42 

1.45 

531 
6.21 
1.17 


1.32 


4.06 
1.04 

458 
1.44 
.97 


Total. 


1,438 
17.53 


1,368 
16.37 


1.439 
16-41 


The  nitrogen  balance  was  as  follows: 

Table  17. — Daily  income  and  outgo  of  nitrogen  in  experiment  No.  19. 


Periods. 


Time. 


Days. 

First  period,  rest 4 

Second  period,  work 4 

Third  period,  rest 3 


Nitrogen. 


In  food.    In  feces.   In  urine.      Gain. 


Grams. 
18.93 
18.33 
18.63 


Grains.  Grams. 

1.44  14.29 

1.37  16.44 

1.35  16.77 


Grams. 
3.20 

.61 


EXPERIMENT  NO.  20. 


This  experiment  began  a  second  set  with  the  same  subjects  as  in 
experiments  Nos.  IT,  18,  and  19.  In  this  set  the  diet  in  the  first  and 
third  periods  contained  less  than  the  normal  amount  of  protein  and 
energy,  and  during  these  periods  little,  if  any,  muscular  work  was 
performed.  In  the  second  period  considerable  muscular  work  was  per- 
formed and  the  energy  value  of  the  diet  was  increased  until  it  was 
equal  in  this  respect  to  a  normal  diet.  During  the  second  period  the 
subject  of  experiment  No.  '20  made  the  trip  up  and  down  hill  fifty-two 
times.  This,  according  to  the  method  of  calculation  followed,  gave 
1,136,356  foot-pounds,  or  49,4^1  kilogrammeters,  equivalent  to  92 
calories,  or  23  calories  per  day. 

Subject. — Chemist  A,  30  years  of  age. 

Weight  {without  clothing). — At  the  beginning  of  the  experiment  69.8  kilograms 
(153.5  pounds);  at  the  end  of  the  first  period  6S.6  kilograms  (151  pounds).  During 
the  second  and  third  period  the  weight  did  not  change. 

Duration.—  The  experiment  began  with  breakfast  March  8,  the  first  period  covered 
four  days.  The  second  period  began  with  breakfast  March  12.  and  covered  four  days. 
The  third  period  began  with  breakfast  March  16,  and  covered  four  days. 


21 


Table  18. — Results  <<(  <  rperimeni  No.  20. 


Labora- 
tory 
num- 
ber. 

Food  materials. 

Weight 

of  ma- 
terial. 

Total 
organic 
matter. 

Nitro- 
gen. 

Protein. 

Fat. 

Carbohy- 
drates. 

Ash. 

Heat  of 
com  bus- 

tion 

calcu- 
lated. 

149 

First  Period 

(  K  EST  ) . 

Digestion  experi- 
ment No.  .'/•"'. 

Grams. 

364 

40 
8,000 
100 
320 
120 
840 

40 
240 
800 

Grams. 

88 
36 

1 ,  042 

99 

288 

109 

565 

37 

240 

2 

Grams. 
7.57 

.10 

if,,  lo 

.75 

7.H4 

1.60 

12.68 

.48 

Grams. 

47 

1 

290 

5 

49 

10 

79 

3 

'nil  ins. 

41 

35 

378 

a rams. 

Grams. 

i 
l 

64 

i  ulories. 

508 

Butter 

504 

Milk 

94 
216 

99 
17.") 

19 
240 

480 

Gelatin 

505 

Oatmeal 

23 

6 
1 
8 
2 

186 

Rice 

507 

Bread 

11 

15 

506 

Potato  chips 

Sugar 

Coffee 

.32 

2 

Total 

2,506 

77.74 

486 

503 

1,517 

86 

13,  769 

Feces  (water-free) 
Urine 

511 

128 
6,705 

92 

6.09 
71.90 

38 

29 

25 

36 

477 
560 

Amount  digested. 

2,414 

71.05 

448 

474 

1,492 

50 

12  732 

Coefficients  of  di- 
gestibility (per 
cent) 

96.3 

92.2 

92.2 

94.2 

98.4 

58.1 

92.5 

Second  Period 

i  Work). 

//.■;,  .v'.-.-.v  SXpen 

ni'  nt  No.  J 16. 

Eggs 

449 

364 
180 

7,408 
100 
320 
120 

1,000 
100 
420 
800 

88 
160 
963 

99 
288 
109 
672 

92 

420 

2 

7.57 

.43 

41.48 

.75 

7.84 

1.60 

15.10 

1.20 

47 

3 

259 

5 

49 

10 

94 

7 

41 
157 
367 

4 
5 
66 

508 

Butter 

515 

Milk 

337 
94 

216 
99 

566 
48 

420 

480 

Gelatin 

505 

Oatmeal 

23 

6 

10 
4 

485 

Rice 

507 

Bread 

12 
37 

506 

Potato  chips 

Sugar 

Coffee 

.32 

2 

Total 

2,893 

76.29 

476 

637 

1,780 

86 

,      16, 063 

Feces  (water- free) 
Urine 

516 

130 
3,858 

98 

6.34 
66.99 

40 

29 

29 

32 

531 
545 

Amount  digested. 

2,795 

69.95 

436 

608 

1,751 

54 

14, 987 

Coefficients  of  di- 
gestibility (per 
cent) 

96.6 

91.7 

91.6 

95.5 

98.4 

62.8 

93  3 

Third  Period 

(Rest). 

Digestion  experi- 
ment No.  217. 

Eggs 

449 

364 

40 

8,000 

100 

320 

120 

840 

40 

240 

800 

88 

36 
1,063 

99 
288 
109 
565 

37 

240 

2 

7.  57 

.10 

44.80 

.75 

7.84 

1.60 

12.68 

.48 

47 

1 

280 

5 

49 

10 

79 

3 

41 

35 

395 

4 

1 

60 

508 

Butter 

520 

Milk 

388 
94 

216 
99 

475 
19 

240 

480 

Gelatin 

505 

Oatmeal 

23 

6 
1 
8 
2 

485 

Rice 

507 

Bread  

11 
15 

506 

Potato  chips 

Sugar 

Coffee 

.32 

2 

Total 

2,527 

76.14 

476 

520 

1,531 

82 

13,981 

Feces  (water-free) 
Urine 

521 

130 
6,971 

95 

6.50 
69.80 

41 

25 

29 

35 

493 
544 

Amount  digested. 

2,432 

69.64 

435 

495 

1,502 

47 

12, 894 

Coefficients  of  di- 
gestibility (per 
cent) 

96.2 

91.5 

91.4 

95.2 

98.1 

57.3 

92.6 

22 


In  the  second  set  of  experiments  the  daily  urine  was  collected  in  one 
portion  during  the  first  (work)  period.  On  the  first  day  of  first  period 
of  experiment  No.  20  the  total  urine  whs  L,890  grams  and  its  nitrogen 
content  0.96  per  cent,  or  18.1  grams;  on  the  second  day  1,750  grams, 
with  a  nitrogen  content  of  1.02  per  cent,  or  17.9  grams;  on  the  third 
day  L,645  grams,  with  a  nitrogen  content  of  1.13  per  cent,  or  18.6 
grams;  and  on  the  fourth  day  1.420  grams,  with  a  nitrogen  content  of 
L.22  per  cent,  or  L7.3  grams.  The  total  nitrogen  eliminated  was  there- 
fore 7.').<->  grams. 

During  the  second  (work)  period  the  urine  was  collected  in  portions 
corresponding  to  eight-hour  intervals.     The  results  follow: 


Table  19. — Amount  of  nitrogen  eliminated  in  tin  urine  (digestion  experiment  No.  .W>). 


Period. 


8  a.  in. 

to 
4  ]>.  m. 


i  p.  in. 

to 

12  p.  rn. 


12  ]>.  in. 

to 
8  a.  in. 


Total. 


First  day: 

Weight  of  urine .grains. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  nrine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


345 
5.00 
1.45 

305 
4.70 
1.54 

282 
5.16 
1.83 

358 
G.19 

1.73 


5.48 
1.81 

353 
7.17 
2. 03 

281 
5.  99 
2.13 

350 

5.99 
1.71 


:..  :;,s 
1.60 

245 
4.70 
1.92 

295 
:>.  4u 
1.83 

405 
.">.  83 
1.44 


984 

15.  SO 


903 

it;.  :.7 


858 
16.55 


1,113 
18.01 


During  the  third  (rest)  period  the  urine  was  also  collected  in  por- 
tions corresponding  to  eight-hour  intervals.  The  amount  of  urine  and 
its  nitrogen  content  are  shown  in  Table  20,  which  follows: 

Table  20. — Amount  of  nitrogen  eliminated  in  the  urine  (digestion  experiment  Xo.  217). 


Period. 


First  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen ..do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine : grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


8  a.m. 

to 
4  p.m. 


448 
5.82 
1.30 

725 
6.53 


770 
6.62 


397 
5.56 
1.40 


4  p.  m. 

to 
12  p.  m. 


1,005 

6.53 

.65 

613 
6.26 
1.02 

,  645 


794 


12  p.m. 

to 
8  a.m. 


473 
5.16 
1.09 

381 

4.84 
1.27 

422 
5.02 
1.19 


2.50 

.84 


Total. 


1,926 
17.51 


1.719 
17.62 


1,837 
18.03 


1,489 
16.64 


28 

From  the  data  given  in  the  preceding  tables  the  balance  of  income 
and  outgo  of  nitrogen  whs  calculated  as  follows: 

Table  21. — Daily  income  and  outgo  of  nitrogen  in  experiment  No.  20. 


Periods. 


First  period,  rest 

Second  period,  work 
Third  period,  rest  . . . 


Time. 


Days. 


Nitrogen. 


In  food. 


Grams. 
19.43 

19.07 
19.04 


In  feces. 


Grams. 
1.52 
1.59 
1.62 


In  urine. 


Grams. 
17. 9* 
16. 75 
17.45 


Gain  (  +  ) 
or 


'in  i, us. 
-0.07 
+  .73 
-  .03 


EXPERIMENT  NO.  21. 

The  experimental  conditions  were  the  same  as  in  the  preceding 
experiment.  The  subject,  a  chemist,  was  23  years  of  age  and  in  good 
health.  During  the  work  period  the  subject  made  the  trip  up  and 
down  hill  68  times.  This  was  calculated  to  yield  1,223,235  foot-pounds, 
or  42,422  kilogrammeters,  equivalent  to  99  calories,  or  25  calories  per 
day.     The  results  of  the  digestion  experiment  follow: 

Subject. — Chemist  B,  23  years  of  age. 

Weight  (without  clothing). — At  the  beginning  of  the  experiment,  56.4  kilograms  (124 
pounds);  at  the  end  of  the  first  period  and  the  beginning  of  the  second  period,  55.9 
kilograms  (123  pounds);  at  the  end  of  the  second  and  the  beginning  of  the  third 
period,  56.4  kilograms  (124  pounds) ;  at  the  end  of  the  experiment,  56.1  kilograms 
(123£  pounds). 

Duration. — The  periods  each  covered  four  days  and  began  with  breakfast  March  8, 
12,  and  16,  respectively. 


24 


Table  22. — Result*  of  experiment  No.  Pi. 


Labora- 
nun,-      Pood  materials, 
ber. 

Weight 

Of  nia- 

terial. 

Total 

organic 

matter. 

Nitr<>- 
gen. 

Protein. 

Fat. 

Carbohy- 
drates. 

A-h. 

Beats  of 

combus- 
tion 
calcu- 
lated. 

449 

First  Period 
(Bee 

Digestion  experi- 
ment Xo.  218. 

drums. 
608 
40 
6,000 
100 
320 
120 
640 
120 
320 
400 

Grams. 

117 

36 

781 

99 

288 

109 

430 

110 

320 

1 

Grams. 
12.65 

.10 
34.80 

.  7"> 
7.84 
1.60 
9.66 
1.44 

(i  rum.--. 

79 

1 

218 

5 

49 

10 

60 

9 

Grams. 

• 

35 

283 

Grams. 

i 

508 

Butter 

504 

Milk 

280 

94 
216 

99 
362 

:.7 
320 

480 

505 

6 

1 
6 
5 

485 

Rice... 

507 

Bread  

B 
44 

506 

Potato  chips 

Coffee  . . . 

.16 

1 

Total  . 

2,  321 

69.00 

432 

461 

1,428 

73 

12  701 

Feces  (water-free) 

512 

115 

4,497 

88 

5.  75 

48.89 

36 

35 

17 

26 

457 
495 

Amount  digested. 

Coefficients  of  di- 
gestibilit\   (per 
cent) 

2,233 

63.  25 

396 

426 

1.411 

47 

11.749 

96.2 

91.7 

91.7 

92.4 

64.4 

92.5 

Second  Period 

(Work). 

Digestion  expt  ri- 
ment  Xo.  219. 

Eggs 

449 

608 
180 
5,408 
100 
320 
120 
800 
180 
500 
400 

147 
160 
703 
99 
288 
109 
537 
166 
500 
1 

12.65 

.43 

30. 28 

.75 

7.84 

1.60 

12.08 

2.16 

79 
3 
189 
5 
49 
10 
75 
14 

68 
157 
268 

6 

5 

41 

508 

Butter... 

515 

Milk  . 

246 

94 
216 

99 
452 

86 
500 

480 

Gelatin 

505 

23 

6 

1 
8 
8 

485 

Rice 

507 

10 
66 

506 

Potato  chips 

Coffee 

.16 

1 

Total . 

2,710 

67.95 

425 

592 

1,693 

75 

14,992 

Feces  (water-free) 
Urine 

517 

111 
4.  061 

87 

5.41 
54.90 

34 

37 

16 

25 

472 

4^y 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent).  ..." 

2, 623 

62.54 

391 

555 

1,677 

50 

14. 031 

96.  S 

92.  0 

92.0 

93.8 

99.1 

66.  7 

93.6 

Third  Period 
(Rest). 

Digestion  ex  per  i- 

m i  lit  Xn.  220. 
Eggs... 

449 

608 
40 
6,000 
100 
320 
120 
640 
120 
320 
400 

147 
36 
797 

99 
288 
109 
430 
110 
320 
1 

12.65 

.10 

33.60 

.75 

7.84 

1.60 

9.66 

1.44 

79 

1 

210 

5 

49 

10 

60 

9 

68 

35 
296 

6 

1 
45 

508 

Butter 

520 

Milk 

291 
94 

216 
99 

362 
57 

320 

480 

Gelatin 

505 

23 

6 
1 
6 
5 

485 

507 

8 
44 

506 

Potato  chips 

Coffee 

.16 

1 

Total 

Feces  (water-free) 
Urine 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent)  

2. 337 

67.80 

424 

474 

1.439 

70 

12,823 

522 

114 
1,624 

87 

5.  62 

54.65 

35 

33 

19 

■j  7 

452 
486 



2, 2.50 

62. 18 

389 

441 

1,420 

43 

11,885 

96.3 

91.7 

91.7 

93.0 

98.7 

61.4 

92.7 

On  fche  first  day  of  the  first  (rest)  period  L,413  grams  of  urine  was 
eliminated,  containing  <».7l>  percent,  <>r  10.2  grams  nitrogen;  on  fche 
second  day,  L,  137 grams  urine,  containing  L.03  per  cent,  or  LI. 7 grams 
nitrogen;  on  the  third  day,  943  grams  urine,  with  1.3  per  cent,  or  1^.4 
grama  nitrogen;  and  on  the  fourth  day,  L,004  grams  urine  containing 
1.4.')  per  cent,  or  L4.6  grams  nitrogen.  The  total  nitrogen  eliminated 
w;i\  therefore,  48.9  grams,  or  L2.2  grams  per  day. 

During  the  second  (work)  period  the  urine  was  collected  iii  por- 
tions corresponding  to  eight-hour  intervals  and  its  nitrogen  content 
determined.     The  details  follow: 

Table  23.     Amount  of  nitrogen  eliminated  in  the  urine  (digestion  experiment  No.  ?19). 


Period. 


First  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do. 

Per  eent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do. . . 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. 

Weight  of  nitrogen do... 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. 

Weight  of  nitrogen do. .. 

Per  cent  of  nitrogen 


8  a.  m. 

4  p.  m. 

12  p.  in. 

to 

to 

to 

1  p.  m. 

12  p.  m. 

s  a.  in. 

568 

315 

143 

5.  15 

4.85 

2.76 

.96 

1.54 

1.98 

502 

258 

203 

."».  37 

4.31 

3.59 

1.07 

1.67 

1.77 

461 

427 

193 

...  1 1 

5.64 

:;.  15 

1.18 

1.32 

1.79 

155 

323 

213 

5.78 

4.55 

3.71 

1.27 

1.41 

1.71 

Total. 


1,026 

13.1)6 


963 
L3.27 

1,081 

14.53 

991 
14.04 

During  the  third  (rest)  period  the  urine  was  also  collected  in  por- 
tions corresponding  to  eight-hour  intervals.     The  results  follow: 

Table  24. — Amount  of  nitrogen  eliminated  in  the  urine  (digestion  experiment  No.  120). 


Period. 


a.  m. 
to 
p.  m. 


First  day: 

Weight  of  urine grams..!  780 

Weight  of  nitrogen do '  6. 24 

Per  cent  of  nitrogen .80 

Second  day: 

Weight  of  urine grams. .  578 

Weight  of  nitrogen do 6. 65 

Per  cent  of  nitrogen 1. 15 

Third  day: 

Weight  of  urine grams. .  655 

Weight  of  nitrogen do 6.  is 

Per  eent  of  nitrogen .99 

Fourth  day: 

Weight  of  urine grams. .  51 13 

Weight  of  nitrogen do 5. 28 

Per  cent  of  nitrogen 1.05 


I  p.  m. 

12  p.  m. 

to 

to 

12 p.  m. 

8a.  m. 

350 

173 

4.73 

2.73 

1.85 

1.58 

225 

197 

3.44 

3.31 

1.53 

1.68 

495 

251 

4.80 

4.02 

.97 

1.60 

280 

137 

1.  12 

2.55 

1.58 

1.86 
1 

Total. 


1,303 
13.70 


1,000 
13.40 


1.401 
15.30 


920 
12.  25 


26" 

The  daily  balance  of  income  and  outgo  of  nitrogen  was  calculated. 
The  results  are  shown  in  the  following  table: 

Table  25. — Daily  income  and  outgo  of  nitrogen  in  exjh  riment  No.  21. 


Periods. 


Time. 


Nitrogen. 


In  food.   In  feces.    In  urine.      Gain. 


First  period,  rest 

Second  period,  work 
Third  period,  rest  .. 


Days. 
4 
4 
4 


drums. 
17.25 
16.99 
16.95 


Grams. 
1.44 
1.85 

1.41 


Grams. 
12.22 
13.73 
13.66 


Grams. 
3.59 
1.91 

1.88 


EXPERIMENT  NO.  22. 

The  experimental  conditions  were  the  same  in  this  as  in  the  two 
preceding  experiments.  The  subject  was  the  same  as  in  experiment 
No.  19.  During  the  first  and  third  periods  the  subject  performed  as 
little  external  muscular  work  as  possible.  During  the  second  period 
a  considerable  amount  of  external  muscular  work  was  performed. 
This  consisted  in  making  70  trips  up  and  down  a  hill  140  feet  high. 
The  work  expended  in  raising  the  body  to  the  height  of  the  hill  was 
calculated  to  3  ield  1,319,799  foot-pounds,  or  45,421  kilogrammeters. 
This  is  equivalent  to  a  total  of  106  calories,  or  an  average  of  24  calories 
per  da}^.     The  details  of  the  digestion  experiment  follow. 

Subject. — Student  C,  22  years  of  age. 

Weiglrf  (without  clothing). — At  the  beginning  of  the  experiment,  65.5  kilograms  (144 
pounds);  at  the  end  of  the  first  period  and  the  beginning  of  the  second  period,  64.3 
kilograms  (141.5  pounds);  at  the  close  of  the  second  and  the  beginning  of  the  third 
period,  65  kilograms  (143  pounds);  at  the  end  of  the  experiment,  64.3  kilograms 
(141.5  pounds). 

Duration. — The  experimental  periods,  each  consisting  of  four  days,  began  with 
breakfast  on  March  8,  12,  and  16,  respectively. 


Table  26.     Results  oj  experiment  No.   ' ;. 


Labo- 
ratory 
Dum- 
ber. 

Pood  materials. 

First  Period 

t  Ki>i 

Digestion    > 

III'  lit    NO.    itl. 

ISggti 

Weight 
of  ma- 
terial. 

Total 

organic 

matter. 

Nitro- 
gen. 

Protein. 

drums. 

:•_' 

1 

218 

5 

(9 

10 
7'.t 
12 

lal. 

Carbon  y 

ilriltrv 

Ash. 

11.  Hi   of 

COmbllS- 

tion 
calcu- 
lated. 

•149 

'hums. 

666 
lit 
6,000 
100 
820 
120 
S40 
L60 
320 
400 

(trams. 
134 

36 
781 

99 
268 
109 
665 
147 
320 
1 

d  rums. 

11.56 

.10 
34.80 
.75 
7.84 
1.60 
12.68 
1.92 

Grams. 

62 

35 

283 

Grams. 

Qrnms. 
6 

1 
is 

6 

I 

7 

Calories. 

Butter 

604 

Milk 

280 
94 

•jk; 

99 
175 

76 
320 

INI 

Gelatin 

605 

( latmeal 

23 

485 

Rice 

607 

Bread  

11 
59 



506 

Potato  chips 

Sugar 



Coffee 

.it; 

1 

Total 

2,480 

71.41 

447 

473 

1,560 

77 

13,446 

Feces  |  water-free 

513 

113 
5,338 

88 

5. 32 
56.  94 

33 

36 

19 

25 

457 
517 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 

2, 392 

66.09 

414 

437 

1,541 

52 

12, 472 

96.  5 

92.6 

92.  6 

92.  I 

'.is.  B 

t,7.  :> 

32  s 

Second  Period 

(Work). 

Digestion    expt  ri- 

mnit  No.  ! 

449 

556 

180 
5, 408 
100 
320 
120 
1,000 
220 
.500 
400 

134 
160 
703 
99 
288 
109 
672 
202 
500 
1 

11.56 

.43 

30.28 

.75 

7.84 

1.60 

15.10 

2.64 

72 

3 

189 

5 

49 

10 

'.»! 

16 

(12 
157 

208 

6 
5 
41 

508 

Butter 

515 

Milk 

246 
94 

216 

99 

566 

in:, 
500 

480 

Gelatin  . 

505 

23 

6 
1 

10 
9 

485 

Rice 

507 

Bread 

12 

81 

506 

Potato  chips 

Sugar 

Coffee 

.16 

1 

Total 

2,868 

70.36 

439 

603 

1,826 

78 

15,726 

Feces  (water-free) 

518 

114 
4,146 

92 

5.23 
62. 45 

33 

41 

18 

22 

499 
507 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent) 

2,  776 

65. 13 

406 

562 

1,808 

56 

14,  720 

96.8 

92.6 

92.5 

93.2 

99.0 

71.8 

Third  Period 
(Rest). 

Digestion    experi- 
ment No.  ! 

449 

556 
40 
6,000 
100 
320 
120 
840 
160 
320 
400 

134 
36 

797 
99 
288 
109 
565 
147 
320 
1 

11.56 

.10 

33.60 

.  75 

7.84 

1.60 

12. 68 

1.92 

72 

1 

210 

5 

49 

10 

79 

12 

62 

35 

296 

6 

1 
45 

508 

Butter 

520 

Milk 

291 

94 
216 

99 
475 

76 
320 

480 

Gelatin 

23 

6 
1 

s 

7 

485 

Rice 

507 

11 
59 

506 

Potato  chips 

Coffee 

.16 

1 

Total  .   . . 

2,496 

70.21 

439 

486 

1,571 

74 

13,568 

Feces  (water-free) 



523 

107 
5,996 

83 

5.16 
62.09 

32 

27 

24 

24 

431 
509 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent) 

2,413 

65.05 

407 

459 

1,547 

50 

12, 628 

96.7 

92.6 

92.7 

94.4 

98.5 

67.6 

93.1 

28 

In  t lie*  first  (rest)  period  of  this  experiment  the  urine  was  collected 
in  a  single  portion  for  each  day.  On  the  iirst  day  952  grams  was 
excreted,  containing  1 .39  per  cent,  or  L3.2  grams  nitrogen;  the  amount 
eliminated  on  the  second  day  was  1,457  grams,  with  a  nitrogen  content 
of  0.96  per  cent,  or  14  grams;  on  the  third  day  1..">:J,7  grams,  with  a 
nitrogen  content  of  0.91  per  cent,  or  14  grams;  and  on  the  fourth 
day  1,392  grams,  containing  1.13  per  cent,  or  15.7  grams  nitrogen. 
The  total  nitrogen  eliminated  in  the  urine  during  the  whole  period 
was,  therefore,  56.9  grams,  or  L4. 2  grams  per  day.  During  the  sec- 
ond (work)  period  the  urine  was  collected  in  portions  corresponding 
to  eight-hour  intervals,  and  its  nitrogen  content  determined.  The 
results  are  shown  in  the  following  table:  v 


Table  27. — Amount  of  nitrogen  eliminated  in  the  urine  {digestion  eocpervment  No. 


Period. 


First  day: 

W.eight  of  urine 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


8  a.  m. 

to 
4  p.  m. 


317 
4.85 
1.53 

335 
5.90 
1.76 

417 
6.05 
1.45 

712 
6.  34 


4  p.  m. 

to 
12  p.  m. 


340 
5.95 
1.75 

260 
4.76 
1.83 

343 
5.  73 
1.67 


4.87 
1.19 


12  i>.  m. 

to 

S  a.  in. 


197 
4.26 
2.16 

255 
5.23 
2.05 

291 
4.54 
1.56 

270 
3.97 

1.47 


Total. 


85 1 
15.06 


850 
15.89 


1,051 
16.32 


1,391 
15.18 


29 

During  the  third  (rest)  period  the  urine  was  as  before  collected  in 
portions  corresponding  to  eight-hour  intervals.  The  amounts  elimi- 
nated and  the  nitrogen  in  it  arc  shown  in  Table  28,  which  follows: 

Table  28. — Amount  of  nitrogen  eliminated  in  the  urine  (digestion  experiment  No.  228). 


Period. 


Firsl  day: 

Weight  of  urine grams. . 

Weighl  "t"  nitrogen do 

Per  criit  of  nitrogen 

Second  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Percenl  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


1  p,  it 

to 


12]..  in. 

to  Total. 


.  III. 

«  a. in. 

639 

157 

5.50 

4.43 

.86 

.97 

K17 

363 

6.54 

4.10 

.80 

1.13 

635 

470 

4.70 

5. 55 

.74 

1.18 

369 

272 

5.54 

3.97 

1.50 

1.46 

l,fi'2X 
15. 68 


1 ,  756 
L5.59 


1,607 
16.02 


1,006 
14.80 


As  was  the  case  in  the  preceding  experiments,  the  daily  balance  of 
income  and  outgo  of  nitrogen  was  determined. 

Table  29. — Daily  income  and  outgo  of  nitrogen  in  experiment  No.  22. 


Periods. 


Time. 


Nitrogen. 


In  food.    In  feces.   In  urine.      Gain 


First  period  (rest) 

Second  period  (work) 
Third  period  i  rest  I... 


Days. 
4 
4 
4 


Grams. 
17.85 
17.59 
17.55 


Grams.  Grams.  Grams. 

1. 33  14. 24               2. 28 

1. 31  16. 61                 .  67 

1.29  L5.52                .71 


EXPERIMENT  NO.  23. 

This  experiment  began  the  third  series  reported  in  the  present  pub- 
lication, which  was  made  with  the  same  young  men  who  had  served 
as  subjects  of  the  preceding  experiments.  The  diet  contained  less 
protein  and  energy  than  normal  and  was  unchanged  during  the  second 
or  work  period.  Except  in  the  second  period,  no  appreciable  amount  of 
muscular  work  was  performed.  During  the  second  period  the  subject 
of  experiment  No.  20  made  the  trip  uphill  55  times.  This  was  calcu- 
lated to  yield  1,201,915  foot-pounds,  or  41,565  kilogrammeters,  equiv- 
alent to  a  total  of  97  calories,  or  an  average  of  24  calories  per  day. 
The  average  results  of  the  digestion  experiment  follow: 

Subject — Chemist  A,  age  30  years. 

Weighi  (without  clothing). — At  the  beginning  of  the  experiment  was  69.8  kilograms 
(153.5  pounds);  at  the  end  of  the  first  period  and  the  beginning  of  the  second 
period,  68.4  kilograms  (150.5  pounds);  at  the  close  of  the  second  and  the  beginning 
of  the  third  period,  67.7  kilograms  (149  pounds);  at  the  close  of  the  experiment,  67.3 
kilograms  (148  pounds). 

Duration. — The  three  experimental  periods,  each  of  four  days'  duration,  began  with 
breakfast  March  22,  26,  and  30,  respectively. 


30 


Table  30. — Reeu&ts  of  experiment  No.  28. 


Labora 

tory 
iiiini- 
ber. 

Pood  materials. 

Weight 

of  ma- 
terial. 

Total 
organic 
matter. 

Nitro- 
gen. 

Protein. 

Fat. 

Carbohy- 
drates. 

Ash. 

Heat  of 

com- 
bustion 

calcu- 
lated. 

449 

First  Period 
I  Rest). 

Digestion  experi- 
ment No.  22k. 

Eggs 

Grams. 
364 

80 
7,  tiOO 
100 
280 
120 
900 

40 
320 
800 

drams. 

88 

70 
966 

99 
252 
109 
604 

36 

320 

2 

Grams. 

7.57 

.24 

41.80 
.75 
6.86 
1.60 
14.31 
.50 

Qrams. 

47 

2 

261 

5 

43 

10 

90 

3 

Grams. 

11 

68 

353 

(•'n  l  ins. 

Grams. 

4 

2 

59 

( 'alortes. 

528 

Hotter 

626 

Milk 

352 

94 
189 

99 
60S 

20 
320 

ISO 

Gelatin 

605 

Oatmeal 

20 

5 

1 

10 

2 

185 

Rice 

627 

Bread 

11 
13 

626 

Potato  chips 

Sugar.. 

Coffee 

.32 

2 



Total 

2, 546 

73.  95 

463 

506 

1,577 

83 

13,917 

Feces  (water-free) 
Urine 

531 

117 
6, 533 

85 

5.  74 
66.  75 

36 

21 

28 

32 

441 
534 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent)  . . .. 

2,461 

68.21 

427 

485 

1,549 

51 

12,  942 

96.7 

92.2 

92.2 

95.9 

98.2 

61.5 

93.0 

Second  Period 
(Work). 

Digestion  experi- 
ment No.  225. 

Eggs 

449 

364 

80 

7,600 

100 

280 

120 

900 

40 

320 

800 

88 

70 
976 

99 
252 
109 
604 

36 

320 

2 

7.57 

.24 

41.04 

.  75 

6.86 

1.60 

14.31 

.50 

47 

2 

257 

5 

43 

10 

90 

3 

41 

68 

353 

4 

2 

55 

528 

Butter 

535 

Milk 

366 
94 

189 
99 

503 
20 

320 

480 

Gelatin 

505 

Oatmeal 

20 

5 

1 

10 

2 

is:, 

Rice 

rv_>7 

Bread 

11 
13 

526 

Potato  chips 

Sugar 

Coffee  

.32 

2 

Total 

2,  noti 

73.19 

459 

506 

1,591 

79 

13, 951 

Feces  (water-free) 
Urine 

536 

118 

4,  274 

87 

5.  82 
62.87 

36 

24 

27 

31 

471 

529 

Amount  digested . 

Coefficients  of  di- 
gestibility (per 
cent) 

2, 469 

67.37 

423 

482 

1,564 

48 

12, 951 

96.6 

92.0 

92.2 

95.3 

98.3 

60.8 

92.8 

Third  Period 

(Rest)  . 

Digestion  expt  /•/- 

ment  No.  226. 

449 

364 

80 

7,600 

100 

280 

120 

900 

40 

320 

800 

88 

70 
1,005 

99 
252 
109 
604 

36 

320 

2 

7.57 

.24 

41.04 

.75 

6.86 

1.60 

14.31 

.50 

47 

2 

257 

5 

43 

10 

90 

3 

41 

68 

381 

4 

2 

60 

528 

Butter 

540 

Milk 

367 
94 

189 
99 

503 
20 

320 

480 

<  relatin 

505 

I  latmeal 

20 

5 

1 
10 

■2 

485 

Rice 

527 

Bread 

11 
13 

528 

l'otato  chips 

Coffee  .. 

.32 

2 



Total 

2,  585 

73.19 

459 

534 

1,592 

84| 

14,219 

Feces  (water-i  reei 
Urine 

541 

121 
5,  988 

88 

5.  88 
68.35 

37 

26 

25 

33 

457 
527 

Amount  digested. 

Coefficients  of  <ii 
gestibility  (per 
cent) 

2, 497 

67.31  | 

422 

508  ! 

1,567 

51 

13,235 

96.  6 

92.0  j 

91.9 

95.1  ' 

98.4 

60.7 

93.1 

8] 

During  the  first  (rest)  period  of  this  se<  of  experiments  t In*  urine 
was  collected  in  a  single  portion  for  each  day.     On  the  first  day  the 

total  amount  of  urine  eliminated  was  1,405  grams,  its  nitrogen  con- 
tent 1.25  per  cent,  or  17.6  grams;  on  the  second  day,  1,913  grams 
urine,  containing  0.86  per  cent,  or  16.4  grams;  on  the  third  day.  1,118 
grams  urine,  containing  1.39  per  cent,  or  15.5  grams;  and  on  the 
fourth  day,  2,097  grains  urine,  containing  0.82  per  cent,  or  17.2  grams. 
The  total  nitrogen  eliminated  during  the  period  was,  therefore,  66.7 
grams,  or  an  average  16.7  grams  per  day.  As  in  previous  experiments, 
the  urine  was  collected  during  the  second  or  work  period  in  portions 
corresponding  to  eight-hour  intervals.  The  table  following  shows 
amount  of  urine  and  the  nitrogen  in  it: 

Table  31. — Amount  of  nitrogen  eliminated  in  the  urine  {digestion  experiment  No.  225). 


Period. 


First  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do — 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


lp 


.  m. 

4  p.  m. 

o 

to 

.  m. 

12  p.  m. 

333 

300 

4.33 

5.19 

1.30 

1.73 

12  p.  m. 
to 

8  a.  m. 


370 
5. 18 
1.40 

457 
5.12 
1.12 

355 

4.9J 
1.40 


233 
4.12 
1.77 

293 
4.81 
1.64 

325 
5. 85 
1.80 


352 

5.  56 

1.58 

497 

6.  51 
1.31 


5.28 
1.39 

379 
5.  95 
1.57 


Total. 


15.08 


1,100 
15.81 


1,130 
15.  21 


1, 059 
16.77 


The  table  below  shows  the  urine  and  its  nitrogen  content  eliminated 
in  the  different  periods  of  the  third  (rest)  period: 

Table  32. — Amount  of  nitrogen  eliminated  in  the  urine  (digestion  experiment  No.  226). 


Period. 


First  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 


8  a.m. 

to 
4  p.m. 


4.80 
1.60 

405 
5.02 
1.24 

427 
4.74 
1.11 

330 
3.89 
1.18 


4  p.m. 

tc 
12  p.  m. 


350 
6.06 
1.73 

368 
5.59 
1.52 

615 

6.03 

.98 


5.14 
1.53 


12  p.  m. 

to 
8  a.m. 


Total. 


618  1,268 

7.  29  18. 15 

1.  is    

850  1,623 

6. 55  17. 16 

.77    

7H7  1,839 

6. 85  17.  62 

.86    

:*■!  1,258 

6.  39  15. 42 

1.08    


32 

The  daily  balance  of   income  and  outgo  of  nitrogen  in  the  three 
periods  of  the  above  experiment  follow-: 

Table  33. — Daily  income  and  outgo  of  nitrogen  in  experiment  No.  .'■>. 


Periods. 


Nitrogen. 


Time. 


In  food. 


First  period,  real  — 
Second  period,  work 
Third  period,  rest  ... 


Days. 
4 

4 
4 


Grams. 

18.49 
18.30 
18.30 


In  feces. 


Grams. 
1.44 
1.46 
1.47 


In  urine. 


Grams. 

16.69 
15.72 

17.09 


Gain(  +  ) 
or 

loss  (-). 


drain*. 
+0.36 
+  1.12 
-  .26 


EXPERIMENT  NO.  24. 

The  experimental  conditions  in  this  were  the  same  as  in  the  pre- 
ceding experiment.  The  subject  performed  during  the  second  or  work 
period  1,349,157  foot-pounds,  or  46,717  kilogramme ters  of  estimated 
muscular  work.  This  was  equivalent  to  109  calories,  or  27  calories 
per  day.  As  in  previous  cases,  the  work  consisted  in  walking  up  and 
down  hill.     The  number  of  trips  made  was  75. 

Subject. — Chemist  B,  age  23  years. 

Weight  (without  clothing). — At  the  beginning  of  the  experiment  56.1  kilograms 
( 123.5  pounds) ;  at  the  end  of  the  first  period  and  the  beginning  of  the  second  period, 
55.9  kilograms  (123  pounds) ;  at  the  end  of  the  second  and  the  beginning  of  the  third 
period,  55.6  kilograms  (122£  pounds);  at  the  end  of  the  experiment.  55.8  kilograms 
(122|  pounds). 

Duration. — The  three  experimental  periods,  each  of  four  days'  duration,  began  with 
breakfast,  respectively  March  23,  26,  and  30. 


33 

Table  34. — Results  of  experiment  No.  $4- 


Food  materials 


Weight      Total 
oi  ma-    organic 
terial.   '  matter. 


First  PERIOD 
(Rest). 

Digestion  expt  ri- 

iii  mt  No.  .'.'.'. 


Eggs 

Butter 

Milk 

Gelatin 

Oatmeal 

Rice 

Bread 

Potato  chips. 

Sugar 

Coffee 


Total 


Feces  I  water-free) 
Urine 


Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent ) 

Second  Period 

(Work). 

Digestion  experi- 
ment No.  ^28. 


i,,  ams. 

608 

Ml 

5,600 

100 
280 
120 

700 

Ml 

500 
400 


Eggs 

Butter 

Milk 

Gelatin 

Oatmeal 

Rice 

Bread 

Potato  chips. 

Sugar 

Coffee 


Total 


Feces  (  water-free) 
Urine 


Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent) 


Third  Period 
(Rest). 

Digestion  expt  ri- 

nu  nt  y<j.  :::<. 




Butter 

Milk 

Gelatin 

Oatmeal 

Rice 

Bread 

Potato  chips. 

Sugar 

Coffee  


Total 


Feces  (water-free) 
Urine 


Amount  digested, 

Coefficients  of  di- 
gestibility (per 
cent) 


Qrams. 

117 
70 
712 

99 

252 
109 
ITU 
74 
500 
1 


101 
4,944 


608 
80 
,600 
100 
280 
120 
700 
80 
500 
400 


105 

894 


80 
5,600 
100 
2S0 
120 
700 
80 
500 
400 


106 
4,225 


Nit  r.  .- 

-■'ii- 


Protein 


Qrams.      (•'rums. 


12.65 

.21 

30.80 

.75 

c.  86 

1.60 

11.13 

1.00 


.16 


2,  356 


65.19 


5.14 

50. 11 


79 

2 

193 

5 
43 

111 
70 
6 


Fat. 


Grams. 

68 

68 

260 


Carbohy-      .  , 

drates.        A  ''■ 


drams. 


20 


259 
94 
189 


41 

500 


1,573 


32 


60. 05 


377  I 


433 


1,546 


96.8 

92.1 

92.2 

147 

12.  65 

79 

70 

.24 

2 

719 

30. 24 

189 

99 

.75 

5 

252 

6.86 

43 

109 

1.60 

10 

470 

11.13 

70 

74 
500 

1.00 

6 

95.8 


98.3 


drams. 

6 

2 

43 


combus- 
tion 
calcu- 
lated. 


Calories. 


68 


23 


66.2 


68 

68 

260 


20 


270 
94 

189 
99 

391 
41 

500 


ID 


2,441 


64.63 


S2 


5.38 
52.42 


2,359         59.25 


405 


1,584 


66 


33 


29 


372 


1,564 


96.  ■ 


22 


66. 


147 

12.  65 

70 

.24 

Tin 

30.24 

99 

.  75 

252 

6.86 

109 

1.60 

470 

11.13 

74 

1.00 

500 

1 

.16 

79 

- 

2 

68 

189 

283 

R 

43 

20 

10 

70 

9 

6 

27 

270 
94 

189 
99 

391 

a 

500 


2,462         64.63 


405 


473 


1,584 


5.51 
56.  75 


21 


2,378         59.12 


371 


444 


1,563 


91.5 


91.6 


1326— No.  117—02- 


13,088 


405 

471 


12.212 


13,111 


414 
465 


12,202 


93.1 


13. 308 


436 

464 


12,  408 


93.2 


34 

On  the  first  day  of  the  first  (rest)  period  the  urine  excreted  amounted 
to  1,324  grams,  with  a  nitrogen  content  of  0.79  per  cent,  or  10.5  grams; 
on  the  second  day  the  amount  of  urine  was  1,073  grams,  its  nitrogen 
content  L. 07  per  cent,  or  11.7  grams;  on  the  third  day  the  subject 
excreted  L,130  grams  urine,  containing  1.20  per  cent,  or  13.6  grams 
nitrogen;  and  on  the  fourth  day  L,397  grams  urine,  containing  LOS 
per  cent,  or  14.4  grams.  The  total  nitrogen  excreted  in  the  period 
was.  therefore,  50.2  grams,  the  average  amount  per  day  12.5  grams. 
In  the  second  (work)  period  the  urine  was  collected  in  portions  cor- 
responding to  eight-hour  intervals.  The  details  of  the  amounts  of 
urine  and  nitrogen  in  it  follow: 

Table  35.—  Amount  of  nitrogen  eliminated  in  the  urine  (digestion  experiment  No. 


Period. 


First  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen : 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do — 

Per  cent  of  nitrogen 

Third  day: 

Weigh t  of  urine grams . . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do — 

Per  cent  of  nitrogen 


The  amount  of  urine  excreted  in  the  different  periods  of  the  third 
(rest)  period,  together  with  its  nitrogen  content,  is  shown  in  the  follow- 
ing table: 

Table  3(3. — Amount  of  nitrogen  eliminated  in  the  urine  (digestion  <  vperiment  No.  229). 


Period. 


8  a.  m. 

to 
4  p.m. 


4  p.  m. 

to 
12  p.m. 


12  p.  m. 

to 
8  p.  m. 


Total. 


First  day: 

Weight  of  urine grams 

Weight  of  nitrogen do.. 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams 

Weight  of  nitrogen do. . 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grams 

Weight  of  nitrogen do.. 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams 

Weight  of  nitrogen do. . 

Per  cent  of  nitrogen 


373 
5.00 
1.34 

433 
5.59 
1.29 

465 
5.35 
1.15 

426 
5.50 
1.29 

384 
4.92 
1.28 

410 
5.13 
1.25 

438 
4.95 
1.13 

465 
5.07 
1.09 

214 
3.85 
1.80 

195 
3.74 
1.92 

218 
4.14 
1.90 

204 
3.51 
1.72 


1. 020 

14.44 


1,086 

14.59 

1,012 
14. 19 

1.107 
13.58 

35 

Following  the  same  met  hods  as  before,  the  daily  income  and  outgo 
of  nitrogen  was  calculated.     Tin4  nitrogen  balance  follow-: 


Table  37.— Daily 

income  and  outgo  of  nitrogen  in  experiment 

No.  .",. 

Periods. 

Tirno. 

Nitrogen. 

In  food. 

In  feces. 

In  urine. 

•lain. 

First  period  (rest) 

Days. 

i 

4 
4 

Cframs. 

16.30 
16.16 

it;.  L6 

(inimtt. 
1.29 
L85 

1.38 

Grams. 
L2.63 
13.11 

14.19 

Grams. 

1.70 

.59 

EXPERIMENT  NO.  25. 

This  experiment  was  made  under  the  same  experimental  conditions 
as  the  two  immediately  preceding.  The  muscular  work  performed 
during  the  second  period  consisted  in  making  the  trip  up  and  down 
hill  75  times,  which  yielded  according  to  the  method  of  calculation 
followed,  1.409,119  foot-pounds,  or  48,849  kilogrammeters.  This  was 
calculated  to  be  equal  to  a  total  of  114  calories,  or  18  calories  per  day. 

Subject. — Student  C,  age  22  years. 

Weight  {without  clothing). — At  the  beginning  of  the  experiment  64.1  kilograms  (141 
pounds).  The  weight  did  not  change  during  the  first  and  second  period.  At  the 
end  of  the  third  period  it  was  64.6  kilograms  (142  pounds). 

Duration. — The  three  experimental  periods,  each  of  four  days'  duration,  began  with 
breakfast  March  22,  26,  and  30,  respectively. 


36 


Table  38. — Results  of  experiment  No.  :■'. 

Labors 
tory 
num- 
ber. 

Food  materials. 

Weight 

of  ma- 
terial. 

Total 
organic 

matter. 

Nitro- 
gen. 

Protein. 

Fat. 

Carbohy- 
drates. 

Ash. 

Heat  of 
combus- 
tion 
calcu- 
lated. 

449 

fib8t  i'kriod 
(Res 

ition  experi- 
ment No.  (SO. 



Grams. 

?84 

100 
280 
120 
900 
160 
.500 
400 

141 

70 

712 

99 

252 

109 

604 

147 

500 

1 

12.15 

.24 

.75 

1.60 

14.31 
2.00 

76 

193 
5 
43 
10 
90 
12 

- 

Grams. 

2 

5 
1 

10 

8 



OalorieL 

Butter 

525 
180 

Milk 

Gelatin 

94 
1*9 

99 
503 

32 

500 



505 

( tatmeal 

20 

Rice 

Bread 

Potato  chip- 

Sugar 

Coffee 

Total 

!••  cea   water-free) 
Urine 

Amount  digested. 

Coefficients  of  di- 
gestibility    per 

527 

11 
53 

.16 

1 

2.  635 

6s..s7 

432 

477 

1.726 

75 

14,089 

533 

90 

4,  514 

68 

4.37 

61.24 

07 

-' 

15 

26 

22 

353 
506 

2.567 

64.  50 

105 

462 

1,700 

13  290 

97.4 

93.7 

93.8 

96.9 

9V.  5 

70.7 

93  9 

Second  Period 

Work). 

Digestion  t.rpfri- 
iiu  nt  No.  . 

449 

584 

80 

5,600 

100 

280 

120 
900 
160 
500 
400 

141 

70 

719 

99 

252 

109 

604 

147 

500 

1 

12. 15 

.24 

30.24 

.75 

6.86 

1.60 

14.31 

2.00 

76 

2 

189 

5 

43 

10 

90 

12 

65 
68 
260 

2 
41 

528 

Butter 

Milk 

Gelatin 

535 
480 

270 
94 

189 
99 

503 

82 

500 



505 

Oatmeal 

20 

5 

1 

10 

8 

4  vi 

527 

Bread 

'    11 
53 

526 

Potato  chips 

Sugar 

Coffee 

Total 

.16 

1 





2,642 

68.31 

42s 

477 

1.737 

73 

14.112 

Feces  (water-free) 
Urine 

Amount  digested. 

Coefficients  of  di- 
gestibility (per 
cent)  ...'. 

Third  Period 
(Rest). 

Digestion  experi- 
ment No.  ess. 

53^ 

100 

3,  2t  -.4 

'■:.. 

5. 02 

59.  40 

31 

28 

13 

22 

417 
496 

2, 565 

63.  29 

397 

449 

1.719 

51 

13, 199 





97.1 

92.  7 

92.8 

94.1 

99.0 

69.9 

93.  5 

449 

584 
80 
5,600 
100 
280 
120 
900 
160 
500 
400 

141 

70 

740 

99 

252 

109 

604 

147 

500 

1 

12. 15 

.24 

30. 24 

.  75 

- 

1.60 

14.31 

2.00 

76 

2 

189 

5 

43 

10 

90 

12 

66 

68 
281 

6 
2 

44 

5  'v 

Butter 

540 

Milk 

270 
94 

189 
99 

503 
82 

500 

505 

20 

5 

1 
10 

485 

Rice 

527 

Bread 

11 
53 

526 

Potato  chips 



Coffee 

.16 

1 

Total 

2,  663 

6s.  31 

428 

498 

1.737 

76 

14.30S 

Feces  (water-free) 
Urine 



543 

110 
3,  >_> 

s7 

5.  3(] 
54.58 

34 

37 

16 

23 

451 

492 

Amount  digested. 

Coefficients  of  di-  : 
gestibility    per 
cent  i  

2,  576 

62  '.'5 

394 

461 

1.721 

53 

13,965 

96.7 

92,  2 

92.1 

92.  6 

99.  1 

69.7   j 

93.4 

37 

On  the  first  day  of  the  first  (rest)  period  the  subject  excreted  842 
grams  of  urine  containing  L.92  percent,  or  L6.2  grams  nitrogen;  on 
the  second  day  910  grams  urine,  containing  L.69  per  cent,  or  L5.4 
grams  nitrogen;  on  the  third  day  the  total  urine  excreted  equaled 
1.im;;>  grams,  its  nitrogen  content  L.37  per  cent,  or  14. *>  grams;  on 
the  fourth  day  of  the  period  the  urine  excreted  equaled  L,697  grams 
with  a  nitrogen  content  of  0.89  per  cent,  or  15.1  grams.  The  total 
amount  of  nitrogen  excreted  in  the  urine  during  the  period  was,  there- 
fore, 61.2  grams,  or  15.3  grams  per  day. 

As  was  the  case  during  the  preceding  experiments,  the  urine  was 
collected  in  the  second  (work)  period  in  portions  corresponding  to 
eight-hour  intervals,  and  its  nitrogen  content  determined.  The  results 
follow. 

Table  39. — Amount  of  nitrogen  eliminated  in  tin  urim  {digestion  experiment  No.  231). 


Period. 


8  a.  m. 

to 
4  p.  m. 


4  p.  m. 

to 
12  p.  m. 


Fi^t  day: 

Weight  of  urine gram<. .  344 

Weight  <>f  nitrogen ■. do j  4.44 

Per  cent  of  nitrogen 1. 29 

Second  day: 

Weight  of  urine gram- . .  299 

Weight  of  nitrogen do 5.17 

Per  cent  of  nitrogen 1. 73 

Third  day: 

Weight  of  urine grams. .  270 

Weight  of  nitrogen do 5.02 

Per  cent  of  nitrogen 1.86 

Fourth  day: 

Weight  of  urine grams. .  277 

Weight  of  nitrogen do 5.  is 

Per  cent  of  nitrogen 1.87 


5.  39 
1.61 


7.20 

1.86 


5.85 
1.90 

319 
6.06 
1.90 


12  p.  m. 

to 
8  a.  m. 


Total. 


190  869 

3. 84  13. 67 

2.02    

165  851 

3.48  15.85 

2.11    

155  733 

3.68  14.45 

2.31    

215  811 

4.19  15.43 

1.95    


The  details  of  the  amount  of  urine  and  nitrogen  in  it  excreted  during 
the  eight-hour  periods  of  the  third  (rest)  period  of  this  experiment  are 
as  follows: 

Table  40. — Amount  of nitrogen  eliminated  intheurim  (digestion  experiment  No. 


Period. 


First  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Second  day: 

Weight  of  urine grams. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Third  day: 

Weight  of  urine grain*-. . 

Weight  of  nitrogen do 

Per  cent  of  nitrogen 

Fourth  day: 

Weight  of  urine grams.. 

Weight  of  nitrogen do 

Per  rent  of  nitiogen 


8  a.m.       4  p.  m. 

to  to 

4  p.  m.      12  p.  m. 


322 
5.22 
1.62 

562 
6.18 
1.10 

180 
2.75 
1.53 


1.33 

4.93 
1.53 

365 
5.62 
1.54 


242 

304 

4.02 

5.02 

1.66 

1.65 

12  p.  m. 

to 

8  a.  m. 


Total. 


3S0  1,182 

3.  .50  15.10 

.92    

1.119 

3.67  H.7> 

1.56    

17o  720 

3.40  11.77 

1.94    

215  761 

3.89  12.98 

1.81    


38 


The  table  below  shows  the  daily  balance  of  income  and  outgo  of 
nitrogen  during  the  whole  experiment: 

Table  41. — DaUy  income  and  outgo  of  nitrogen  in  experiment  No. 


Periods. 


First  period,  rest 

Second  period,  work 
Third  period,  rest  .. 


Time. 


Days. 
4 
4 
4 


Nitrogen. 


In  food.    In  feces.    In  urine. j     Gain. 


Grams. 
17.22 
17.08 
17.08 


Grams.  Grams. 

1.09  15.31 

1.26  14. 85 

1.34  13.65 


Grams. 
0.  B2 


- 


SUMMARY  OF  COEFFICIENTS  OF  DIGESTIBILITY. 

In  the  preceding  pages  data  are  given  which  show  the  amount  of 
protein,  fat,  and  carbohydrates  digested,  as  well  as  the  energy  of  the 
total  digested  food.  Such  data  are  summarized  in  Table  42.  the  results 
being  compared  with  those  obtained  in  the  similar  investigation  pre- 
viously reported/' 

Table  42. — Summary  of  coefficients  of  digestibility  of  a  simple  mixed  diet,  and  the  energy 

available. 


Num- 
ber of 
experi- 
ment. 


206 

207  i 

208 

209  | 

210 

211 

212 

213 

214 

215 

216 

217 

218 

219 

220  ' 

221 

222 

223 

224 

225 

226 

•227 

228 

229 

230 

231 

232  , 


Sub- 
ject. 


Character  of  experiment. 


Protein. 


Fat. 


Carbohy- 
drates! 


Energrv 


Rest 

Work 

Rest 

do 

Work 

Best 

do 

Work 

Rest 

do 

Work 

Rest 

do 

Work 

Rest 

do 

Work 

Rest 

do 

Work 

Rest 

do 

Work 

Rest 

do 

Work 

Rest 

Average,  rest  experiments: 

A.  6  experiments 

R.  6  experiments 

C  6  experiments 


Average,  18  experiments. 


Average,  work  experiments: 

A,  3  experiments 

B,  3  experiments 

€,  3  experiments 


Average.  9  experiments 

Average,  all  (27)  experiments  . 


Per  cent, 

91.6 

91.2 

92.2 

92.0 

91.5 

91.5 

92.4 

92.6 

92.9 

92.  2 

91.6 

91.4 

91.7 

92.0 

91.7 

92.6 

92.5  I 

92.7 

92.  2 

92.  2 

91.9 

92.2 

91.9 

91.6 

93.8 

92.8 

92.1 

91.9 
91.8 
92.7 


Per  cent 

95.9 
96.4 
96.7 
94.0 
94.0 
94.1 
94.3 
92.  7 
94.8 
94.2 
95.5 
95. 2 
92.4 
93.8 
93.0 
92.4 

94.' 4 
95.9 
95.3 
95.1 
95.8 
93.6 
93.9 
96.9 
94.1 
92.6 

95.5 
93.9 
94.2 


92.1 


Per  cent. 


98.3 
98.4 
98.4 
98.3 
98.6 
98.4 
98.4 
98.4 
98.1 

99.1 
98.7 
96.8 

99.0 
98.5 
98.2 
98.3 
98.4 


94.5 


98.7 

98.5 
99.0 
99.1 


,b 


Per  cent. 

92.6 
92.7 
93.0 
93.0 
92.9 
93.0 
93.1 
93.0 
93.4 
92.  S 
93.3 
92.6 
92.5 
93.6 

92.  7 
92.8 
93.6 
93.1 
93.0 
92.8 
93.1 
93.3 
93.1 
93.2 
93.9 

93.  5 
93.4 

92.8 
93.0 
93.3 


92. 2 

94.5 

98.4  ' 

93.0 

91.7 

91.8 
92.6 

95.7 
93.8 
93.3 

98.2  | 
98.7 

98.9  1 

92.9 
93.  2 

93.4 

92.0 

94.3 

98.  6 

93.2 

93.1 


a  U.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  89. 


89 

From  the  table  it  appears  thai  there  was  practically  no  difference 
in  the  average  thoroughness  of  digestion  of  the  ration  when  tin*  sub- 
jects rested  unci  when  they  performed  rather  severe  muscular  work. 
Slight  variations  are  noticeable  in  the  coefficients  of  digestibility 
obtained  with  the  different  subjects,  but  these  are  not  sufficient  forgen- 
eral  deductions.  Individuality  appeared  to  have  much  less  effect  upon 
the  digestion  than  might  be  expected.  The  average  results  agree 
quite  closely  with  those  previously  obtained  when  it  is  remembered 
that  the  diet  in  the  two  series  of  experiments  though  similar  was  not 
the  same.  Considering  the  experiments  as  a  whole,  the  differences  in 
coefficients  of  digestibility  between  the  periods  of  work  and  rest  are 
Less  marked  than  those  observed  when  the  conditions  as  regards  work 
performed  were  uniform.  This  is  strong  evidence  that  the  average 
results  of  a  considerable  number  of  digestion  experiments  may  be 
assumed  to  actually  represent  the  digestibility  of  the  different  nutrients 
in  a  given  diet,  and  that  such  averages  may  be  used  in  calculation. 

METABOLISM  OF  NITROGEN. 

The  income  and  outgo  of  nitrogen  was  determined  in  the  experiments 
reported  in  this  bulletin,  the  special  object  being  to  secure  information 
regarding  the  nutrients,  which  are  the  actual  source  of  muscular  work. 
It  was  assumed  that  if  protein  was  required  for  performing  external 
muscular  work  more  nitrogen  would  be  excreted  in  the  urine  under 
the  experimental  conditions  in  the  period  in  Avhich  muscular  work  was 
performed  than  in  the  periods  in  which  the  subject  remained  as  inac- 
tive as  possible.  There  are  those  who  maintain  that  muscular  work  is 
performed  at  the  expense  of  nitrogen- free  nutrients,  and  that  under 
ordinary  circumstances  protein  is  not  the  source  of  energy,  but  is 
required  for  the  formation  and  repair  of  body  tissue.  Other  physiolo- 
gists hold  that  while  nitrogen-free  nutrients  are  usually  the  source  of 
muscular  energy,  yet,  if  the  work  is  protracted  enough,  or  severe 
enough  to  induce  labored  breathing,  the  energy  must  be  supplied  by 
protein.  Judging  by  the  results  of  the  investigations  conducted  under 
the  auspices  of  this  Department,  it  appears  that,  provided  the  carbohy- 
drates and  fat  in  the  diet  are  abundant  and  the  protein  is  not  excessive, 
the  nitrogen-free  nutrients  are  the  usual  source  of  energy  for  external 
muscular  work. 

In  the  early  experiments  made  at  the  University  of  Tennessee  the 
diet  was  quite  abundant,  and  under  the  different  experimental  condi- 
tions little  change  in  the  amount  of  nitroo-en  excreted  in  the  urine 
was  observed,  which  could  be  attributed  to  an  increased  metabolism  of 
protein  in  the  work  periods.  In  the  present  experiments  the  diet  was 
more  limited  in  amount,  though  in  the  majority  of  eases  it  was  normal 
in  the  proportion  of  nitrogen-free  to  nitrogenous  nutrients. 


40 

The  balance  of  income  and  outgo  of  nitrogen,  as  well  as  the  available 

energy  in  a  food,  and  the  average  heat  equivalent  of  the  work  per- 
formed in  the  different  work  experiments,  is  shown  in  the  following 
table: 

Table  43. — Daily  incorru   and  outgo  of  nitrogen  and  energy  in  metabolism  experiments 
Nob.  17-25,  with  work  actually  measured. 


a,  .    a 

--    --  •_ 


IS 


19 


20 


21 


22 


23 


24 


25 


206 
207 
208 
209 

■Jio 
211 

212 
213 

1214 
215 

•JIG 
■217 
218 
219 
220 
221 
222 
223 
224 
225 
226 
227 
228 
229 
1230 
^231 
232 


Character 
of 
experi- 
ment 


Rest  . 
Work 
Rest  . 
Rest  . 
Work 
Rest  . 
Rest  . 
Work 
Rest  . 
Rest  . 

Work 

Rest  . 
Rest  . 
Work 
Rest  . 
Rest  . 
Work 
Rest  . 
Rest  . 
Work 
Rest  . 
Rest  . 
Work 
Rest  . 
Rest  . 
Work 
Rest  . 


Nitrogen. 


II 


Kgs. 

A 

-0.45 

A 

A 

R 

4-  .34 

B 

-   .34 

B 

+  .23 

c 

-  .23 

(' 

e 

A 

-1.13 

A 

A 

R 

-  .45 

B 

+   .45 

R 

-  .23 

C 

-1.13 

(' 

+  .68 

c 

-  .68 

A 

-1.36 

A 

-  .23 

A 

-    .45 

R 

-   .34 

B 

-  .34 

R 

-f  .23 

(' 

<"' 

C 

-   .45 

Gins. 
20.88 
20.08 
20.48 
18.54 
17.94 
18.24 
18.93 
18.33 
18.63 
19.43 
19.07 
19.04 
17.25 
16.99 
16.95 
17.85 
17.59 
17.55 
18.49 
18.30 
18.  30 
16.30 
16.16 
16.16 
17.22 
17.08 
17.08 


Gms. 

1.75 
1.74 
1.60 
1.51 
1.51 
1.57 
1.44 
1.37 
1.35 
1.52 
1.59 
1.(12 
1.44 
1.35 
1.41 
1.33 
1.31 
1.29 
1.44 
1.46 
1.47 
1.29 
1.35 
1.38 
1.09 
1.23 
1.34 


Gms. 

17.56 
17.92 
17.61 

13.  01 
14.28  I 
14.1s 

14.  29 

16.  44 
16.77 
17.98 
16.75 

17.  45 
12.  22 
13.73 
13.66 

14.  24 
15. 61 

15.  52 
16.69 
15.  72 
17.  09 

12.  53 
13.11 
14.19 
15.  31 
14.  85 

13.  65 


Gms. 
+  1.57 
4-  .42 
+1.27 
+4.02 
+2.15 
+2.49 


4-3.20 
+  .52 
+  .51 

-  .07 
+  .73 

-  .03 
+3.59 
+1.91 
+1.88 
+2.28 
+  .67 

-  .74 
+  .36 
-1.12 

-  .26 
+2.48 
+1.70 

-  .59 
+  .82 
+  .97 
+2.09 


Energy, 


Work 

measured. 


Calo- 
ries. 

3,960 
3,  912 
3,898 
3.  687 
3, 651 
3,  640 
3,848 
3,812 
3,802 
3,  442 
4,016 
3.4S3 
3.175 
3,748 
3. 206 
3.  361 
3, 932 
3,  392 
3.  479 
3,488 
3.  555 
3.272 
:;.27s 
3.327 
X.  522 
>28 


g 

- 

« 

= 

~ 

Galo- 

rit  8. 

vies. 

143 

149 

142 

143 

124 

lis 

E 


-        -         < 


126  133 

133  128 
126  130 
128  137 

134  132 

in;  ion 

119  140 
133 

123 
114 


118 


101 
111 


136 

136  i 

124 

122 


113  121 

114  129 
125  127 
108  127 
lio  153 
lis  132 
114  132 


118 

116 


109  116 

ss  126 

104  124 

113  123 


ties. 

3,668 
3,627 
3, 626 
3,428 
3.390 
3,384 
3,583 
3,  -546 
3.  550 
3,183 
3.747 
3.224 

2.  937 

2,972 
3,118 

3.157 

3.  236 
3.23s 
3.  309 
3,053 
3,  051 
3.102 
3.308 
3,300 
3,  341 


K<tm$.     ties. 


55,  876     130. 4 


114.0 


50.992     119.0 


K  421        92. 0 


42.422        99.0 


45,  421      106.  0 


97.  0 


4.1.717      109.0 

ii+o 


No  constant  difference  was  observed  in  the  amount  of  nitrogen 
excreted  in  the  urine  in  different  periods  which  could  be  attributed  to 
the  muscular  work  performed. 

COMPOSITE  SAMPLES. 

A  considerable  part  of  the  labor  involved  in  conducting  experiments 
like  those  reported  in  this  bulletin  is  due  to  the  fact  that  each  food 
material  is  analyzed.  It  was  believed  that  if  a  composite  sample  was 
made  up  of  aliquot  portions  of  the  different  foods  in  any  given  ration 
fche  analysis  of  such  sample  would  show  the  average  composition  of 
the  ration  as  a  whole.  To  determine  the  accuracy  of  this  method, 
composite  samples  were  made  of  the  diet  supplied  in  sixteen  of  the 
experiments   reported  in  this  and  a  former  bulletin."  and  the  results 


a  U.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bill.  89. 


41 

compared  with  the  average  values  for  the  ration  computed  from  the 
analyses  of  the  different  foods  composing  it.  Sugar  was  not  included 
in  the  composite  sample,  and  tin4  data  derived  from  the  analysis  of 
sugar  are  also  omitted  in  computing  the  average  composition  of  the 

ration  from  the  analyses  of  individual  foods.  It  was  believed  that  this 
omission  would  not  affect  the  value  of  the  results,  as  sugar,  of  course, 
contains  no  nitrogen;  furthermore,  it  was  convenient  to  omit  the  sugar 

as  at  best  the  composite  sample  was  bulky  and  therefore  rather  difficult 
to  handle  satisfactorily.  .1 

In  experiments  Nos.  53,  56,  anil 59  the  ration  consisted  of  Hamburg 
steak,  butter,  milk,  oatmeal,  bread,  and  potato  chips.  In  experiments 
Nos.  62  and  6d  the  ration  was  made  up  of  the  same  materials,  except 
that  Hamburg  steak  was  omitted  and  cracked  corn  was  added.  The 
ration  in  experiments  Nos.  99,  102,  and  105  was  made  up  of  milk,  oat- 
meal, potato  chips,  bread,  canned  beef,  and  butter.  In  experiment 
No.  108  the  ration  was  the  same  in  character,  except  that  gelatin  was 
added.  Sugar  was  used  in  all  the  rations,  but,  as  previously  noted, 
was  not  included  in  the  comparison.  In  some  of  the  experiments  coffee 
was  taken  as  a  beverage,  but  the  amount  of  nutrients  thus  added  to 
the  ration  is  so  small  that  it  is  believed  that  this  material  may  be  left 
out  of  account  without  introducing  any  appreciable  error. 

In  nine  of  the  tests  (digestion  experiments  Nos.  53,  56,  59,  62,  65, 
99, 102,  105,  and  108)"  one-fifth  of  the  total  amount  of  the  several  food 
materials  was  taken  as  an  aliquot  portion.  In  seven  later  tests  (diges- 
tion experiments  Nos.  117,  150,  153,  156,  159,  165,  and  168)  the  pro- 
portion was  diminished  to  one-tenth.  In  these  tests  the  analyses  of 
the  composite  samples  were  made  in  duplicate  to  study  still  further 
the  accuracy  of  the  method.  It  seemed  probable  that  if  the  composite 
sample  did  not  represent  very  closely  the  average  composition  of  the 
ration,  or,  in  other  words,  if  it  was  not  a  uniform  mixture,  the  dupli- 
cate analyses  would  not  agree  at  all  closely. 

The  materials  making  up  the  composite  sample  were  thoroughly 
mixed  and  then  dried,  ground,  subsampled,  and  analyzed  in  the  usual 
way. 

The  calculated  composition  of  the  ration  was  learned  by  dividing 
the  sum  of  the  amounts  of  any  given  nutrient  in  the  several  foods  by 
the  total  nutrients  in  the  ration.  Thus  in  experiment  No.  53  the  total 
weight  of  organic  and  mineral  matters  in  the  food,  leaving  out  the 
sugar  as  already  explained,  was  1,252  grams.  The  total  protein  in 
the  different  articles  making  up  the  diet  was  267  grams.  Therefore  the 
ration  as  a  wThole  contained  21.33  per  cent  protein  (267-^1.252  =  21.33 
per  cent). 

In  Table  14  a  comparison  is  made  of  the  results  obtained  by  analyz- 

*TJ.  S.  Dept,  Agr.,  Office  of  Experiment  Stations  Bui.  89. 
1326— No.  117-02 1 


42 

ing  the  composite  samples  of  the  several  rations  and  by  calculating 
their  composition  from  the  analysis  of  the  several  food  materials. 

Table  44. — Quantities  and  proportions  of  nutrients  in  ration  computed  from  comp 
of  individual  food  materials  and  from  that  of  the  composite  sample. 


Quantities  of  nutrients  in  ration  for    Percentage  composition  of  water- 
four  days.  free  material. 


Character  of  analyses. 


Protein.      Fat. 


Carbohy-I 
drates. 


Ash.      Protein.       Fat. 


Carbohy- 
drate^ 


Ash. 


Experiment  No.  53: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  56: 

By  individual  analyses 
By  composite  analysis.. 

Experiment  No.  59: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  62: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  65: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  99: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  102: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  105: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  108: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  206: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  209: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  212: 

By  individual  analyses  . 
By  composite  analysis. . 

Experiment  No.  215: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  218: 

By  individual  analyses  , 
By  composite  analysis. . . 

Experiment  No.  224: 

By  individual  analyses  . 
By  composite  analysis. . . 

Experiment  No.  227: 

By  individual  analyses  . 
By  composite  analysis. . . 


IMS. 

267 
268 

'•ranis. 
390 
385 

278 
282 

296 
296 

295 
300 

311 
322 

218 
218 

271 
266 

239 
239 

271 
276 

248 
263 

279 

271 

185 
192 

212 
199 

210 

226 

243 
239 

262 
266 

307 
293 

522 

544 

559 
585 

464 
486 

517 
532 

473 
47> 

521 
532 

486 
494 

503 
493 

432 
428 

461 
448 

463 
473 

506 

470 

409 
406 

452 
463 

<,  rums.      <  j  rums. 

:.17  J- 

551  47 


545 
539 


521 
505 


456 
460 


579 
572 


570 


562 

-568 


563 
550 


646 


1840 
1781 


1751 


1885 
1856 


1517 
1515 


1428 

1443 


lo77 
1600 


1573 
1565 


48 


35 


90 


83 


Percent. 
21.33  , 
21. 43 

24.  21 
25. 11 

22.18 
22. 1-1 

21. 19 
21.20 

21.  77 
23.13 

18.67 
19.39 

19.  98 

21.47 

20.81 
21.11 

IS.  10 

16.54  , 

17.31 

16.02  | 
16.20 

18.75 
19.04 

18.04  I 
17.87 

17.61  ! 
IS.  00  i 

16.35 
16. 21 


/''  /■  et. 

31.15 
30.78 

26.  45 

25.48 

26.47 
27.38 

27.  -56 
27.03 

24.  03 
24.48 

24.  .50 
23.82 

21.39 
20.07 

23.12 
22.79 

24.39 
23.  31 


Per  cent. 
43.69 
44.03 

46.86 
46.37 

44.  34 
43.00 

46.39 

46.77 

51.33 

•50.73 

.50.04 
49.70 


56.  71 
57.36 


53. 57 
52. 34 


51.31 
52.11 


18.60 
19.46 

61.24 
59.27 

18.43 
18.97 

62.  43 
60.59 

17.64 
18. 01 

63.84 
62.85 

19.40 
19.00 

58.  .50 

19.  26 
18.73 

59.65 
60. 26 

19.25 
17.86 

59.99 
60.88 

18.07 
18.50 


62.  86 
62.-56 


ft  r  ct. 
3.83 
g.  76 


3.94 


4.08 
4.09 


3.87 


3. 45 


3.35 


3.23 
3.18 


3!  40 


3.50 
3.47 


2.79 
3.17 


2.60 
3.13 


2.50 
2.94 


3.32 
3.46 


3.05 
3.14 


3.15 
3.26 


2.72 
2.73 


It  will  be  seen  that  the  agreement  between  the  composition  of  the 
ration  as  shown  by  the  analysis  of  composite  samples  and  as  computed 
on  the  basis  of  analyses  of  individual  foods  is  quite  close.  When  the 
results  of  duplicate  analyses  of  the  same  composite  sample  were  com- 
pared the  same  close  agreement  is  found.  In  accordance  with  the 
usual  practice,  these  data  are  not  reported.  In  all  cases  the  discrepan- 
cies are  not  greater  than  are  to  be  expected  from  the  analysis  of 
different  samples  of  such  foods  as  meat,  fish,  etc..  or  in  some  cases 
even  in  duplicate  analyses  of  the  same  sample.  Furthermore,  it  must 
be  remembered  that  the  calculated  composition  of  the  ration  includes 
the  result  of  all  the  errors  in  the  analysis  of  the  different  foods.  The 
proportion  of  error  in   the   anlysis   of  composite  samples  it   would 


48 
appeal-  must  be  lower,  as  the  total  Dumber  of  determinations  is  nol 

nearly  as  Large. 

It  is  interesting  to  compare  the  coefficients  <>t'  digestibility  obtained 

in  the  different  work  and  rest  periods  in  the  earlier  experiment- at 
the  University  of  Tennessee  and  those  reported  herewith  when  the 
composition  of  the  ration  is  obtained  by  the  two  methods. 

Table  4">. —  ( '<><  ijiri,  ntsof  digestibility  of  nutrients  computi  dfrom  composition  of  individual 
food  materu  Is  and  from  thai  of  composite  samples. 


Character  of  analyses. 


Experiment  No.  58: 

By  individual  analyses 
By  composite  analysis. . 
Experiment  No.  56: 

By  individual  analyses. 
By  composite  analysis. 
Experiment  No.  59: 

By  individual  analyses 
By  composite  analysis. . 
Experiment  No.  62: 

By  individual  analyses. 
By  composite  analysis.. 
Experiment  No.  65: 

By  individual  analyses 
By  composite  analysis  . 

Experiment  No.  99: 

By  individual  analyses. 
By  composite  analysis. 

Experiment  No.  102: 

By  individual  analyses. 
By  composite  analysis. . 

Experiment  No.  106: 

By  individual  analyses 
Bv  composite  analysis  . 

Experiment  No.  108: 

By  individual  analyses. 
Bv  composite  analysis. . 

Experiment  No.  206: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  209: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  212: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  215: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  218: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  224: 

By  individual  analyses 
By  composite  analysis. . 

Experiment  No.  227: 

By  individual  analyses 
By  composite  analysis. . 


Protein.       Fat.       ^Sfi7"      Ash.        Energy. 


Per 


<■>  at. 

94.4 
94.4 

94.2 
94.3 

94.2 
94.3 

91.7 
91.8 

93.3 
93.3 

92.7 
93.2 

91.4 
91.7 

92.9 
93.4 

92.8 
92.9 

91.6 
91.9 

92.0 
92.4 

92. 4 
92.5 

92.2 
92.3 

91.7 
91.6 

'.''J.  2 
92.4 

92.  2 

92. 1 


/•<  ;•  cent. 
96.9 
96.9 

94.9 
94.9 

94.9 
95.0 

97.0 
97.0 


96.7 
96.8 


95.7 
95.6 


ss.  -1 
87.4 


95.  5 

95.4 


94.5 
94.2 


95.9 
96.1 


94.0 
94. 2 


94.3 
94.4 


94.2 
94.1 


92.4 
92.2 


95.9 
95.5 


95.  9 


drates 


Per  cent. 
96.1 
96.2 


98.0 
98.0 


96.5 
96.5 


95.9 
95.9 


97.6 
97.6 


96.8 


98.2 
98.2 


96.1 
96.0 


97.5 

97.6 


97.7 
97.6 


98.3 
98.  2 


98.2 
98.3 


98.3 
98.3 


Percent.  Percent. 

66.  7  90.  8 

66.0    

65.9  90.8 

67.4    

66. 7  88. 9 

66.7    

55.3  91.2 

56.4    

61.5  91.2 

62.5    

52.4  90.0 

47.4    

56.3  88.8 

56. 3    

62. 9  S9.  4 

63.9    

56.8  90.1 
56.8  i 

56.0    

61.0    

6/.1    

72.7    

67.6    

72.4    

68.1    

60.0    

64.4    

65.3    

61.5  .... 

62.  8    

2    


The  agreement  between  the  results  obtained  by  the  two  methods  is 
again  seen  to  be  very  close. 

From  the  results  of  the  above  comparisons  it  seems  fair  to  conclude 
that  the  composition  of  a  given  diet  may  be  learned  with  reasonable 
accuracy  by  the  analysis  of  a  composite  sample  made  up  of  aliquot 
portions  of  the  different  foods  in  the  ration,  and  that  this  method  may 
be  advantageously  followed  in  digestion  experiments  and  similiar 
investigations  where  the  amount  of  analytical  work  is  at  best  neces- 
sarily large. 


■Hi! 


